Tekhelet: Color Perception or Apprehension?

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by Efraim Vaynman

Tekhelet, most say it is blue, others argue it is purple, and still others describe it as green. Let us reexamine the subject anew as we approach Parshat Shelah that contains the mitzvah of tzitzit and tekhelet.

A Scottish eye care company recently commissioned a study to “demonstrate just how our visual interpretations of the world around us can differ quite sharply, even on a very basic level.”1 Participants were shown a swatch and asked to determine whether it was blue or green. While most respondents (64%) correctly identified the color as green, almost a third (32%) identified the color of the swatch as blue. Much like the viral meme #TheDress2, the study exposes that differences in the perception of color are much more prevalent than people realize.

One can imagine that if in our modern globalized world there is such dissonance about the perception of color among people of the same country, there was probably little unanimity about color in the ancient world, especially amongst divergent countries, cultures, and languages.

The very concept of color in our western world may not even have had an exact correlate in ancient civilizations. We think of color in Newtonian terms, namely, as a mixture of base colors which form a particular hue, but color does not inform us of the other visual percept qualities such as depth, brightness, temperature, irradiance, opacity, and texture.

Color was not always so abstract. In ancient times colors were referred to by noting their similarity to other items in nature with a known particular visual characteristic. This is similar to the way the English language uses the word orange to refer to things that have the same color as the fruit. If one were to say today that a particular thing is orange colored, we would know that it’s hue is what we refer to as orange without imparting that it was similar to an orange in any other way. However, in ancient times this was not necessarily true. The ancient Greek term for color is khrôma (χρῶμα) which primarily meant surface, particularly the skin, and only sometimes was it used to describe things of color such as paint or dyes. The Latin word color had similar connotations. To describe the color was to describe the outside skin or surface of something, including but not limited to its color hue. To say that something has an orange-like color in ancient times could mean that this thing is similar to the skin or outside of an orange in a number of ways, including color, smoothness, or shininess.

This different perception of color in the ancient world is something we must keep in mind when trying to analyze and reconstruct colors based on the way they are described in ancient sources. In an effort to better understand this mitzvah, this essay will address the following pertinent question: what is the color of tekhelet and how did modern researchers determine the color after being lost for over 1300 years?

The Rediscovery of Tekhelet

The quest for tekhelet started in 1888 when Rabbi Gershon Hanoch Leiner, the Radziner Rebbe, stirred the European rabbinate with three books he authored in which he proposed to find the hilazon, the source of tekhelet, based on inferences from Talmudic sources. His search culminated with a visit to an aquarium in Italy where he identified a certain squid (Sepia officinalis) as the source of tekhelet from which he managed to produce a Prussian blue dye, which some Radziner and Breslover chassidim wear till this day. Rabbi Leiner’s suggestion was never widely accepted, and it was later discovered that the Prussian blue dye was a result of a chemical process rather something derived from the squid itself. He did, however, manage to spark the search for tekhelet.

In 1914, Rabbi Isaac Herzog, later the first chief rabbi of Israel, defended his dissertation, Semitic Porphyrology,3 about the search for tekhelet. This excellent work is still the most comprehensive treatise on the subject. While Rabbi Herzog did not come to a conclusive resolution for the source of tekhelet, he did feel that he had firmly proven its original color. In Rabbi Herzog’s words: “I believe conclusively, that if not actually so in the strictly scientific sense, the tekelet­-colour did not, at all events, appreciably differ from a dark pure blue, the nuance assigned to it by tradition.”4 Elsewhere he says it is what an English man calls “deep dark blue”.5

Though he very much longed to do so, Rabbi Herzog never did produce tekhelet from either of the two snails he strongly considered in his dissertation.6 He had doubts about both possibilities but his questions were not enough to conclusively dismiss either one as the source of the tekhelet. Problems with creating an actual dye were more practical because at the time scientist had not found a way to create a color fast dye from either snail.7

Despite his assuredness about the true color of tekhelet, Rabbi Herzog was not absolutely certain that tekhelet was a pure blue. He was willing to allow a degree of violet because “there are very persuasive reasons to believe that the species known as Murex trunculus is the hilazon of tekhelet. For one, the dye that it emits is sufficiently blue.”8 At the time it was not yet known how to produce a pure blue dye from the Murex trunculus. Although Rabbi Herzog would tolerate a blueish violet color, he believed that it was likely possible to create a pure blue dye from the Murex trunculus if we only knew the precise sub-species and correct way of dyeing.9

Eventually a method was found to create a pure blue dye from the Murex trunculus.10 In 1988 Rabbi Eliyahu Tavger managed to dye wool blue from the Murex trunculus and tie his tallit with the strings.11 A few years later, in 1993, the Ptil Tekhelet organization was founded to manufacture and promote the wearing of sky-blue12 tekhelet for the mitzvah of tzitzit.

The Question of Color

The question of the color of tekhelet is a modern one. From biblical times the colors of the Torah were a living tradition mimetically transmitted from generation to generation. There was no need to describe color because it was learned; if not as part of the language they spoke then at the very least tekhelet was something with which they were intimately familiar with from everyday religious life. When Jewish sources mention tekhelet they are almost always speaking of its symbolism or relationship to other things and not of its color which was well known and needed no description. It isn’t until tekhelet was lost or became too scarce to be familiar to everybody that there was an attempt to describe its color.13

Although a description of the color of tekhelet may not have been needed for Jews living contemporaneous with tekhelet, non-Jews were not familiar with the word. The earliest sources that describe tekhelet are translations of the Torah. The Septuagint, Aquila14, Symmachus15, Theodotion16, and the Vulgate17 were all translations that were written at the time that tekhelet was still in use. The translations are unanimous that the translation of tekhelet in Greek is ὑάκινθος18 (hyákinthos); the Latin equivalent hyacinthum19 is found in the Vulgate. The same translation for tekhelet is also found in Josephus’20 and Philo’s21  Greek writings.

The problem is that these translations are equally ambiguous to us. The word hyákinthos as the name of a colored fabric rarely occurs outside of the translations of the Bible and when it does it is still unclear the color intended.22 The color of hyákinthos fabric was probably similar to the flower and the precious stone which both bear the same name. Rabbi Herzog argued that the translation could not be used to determine the color of tekhelet because hyákinthos was variably used to describe both violet and blue.

Rabbi Herzog instead argued that the most reliable sources attesting to the color of tekhelet can be found in the Talmud, which in his opinion seem to clearly indicate that tekhelet was blue.

The best proof from the Talmud according to Rabbi Herzog is that in several places it warns against substituting dye from kla ilan (indigo)in place of tekhelet, which, according to Rabbi Herzog, clearly demonstrates that the color from the two dyes were identical.23 The Talmud even devises a test for one who is unsure if he has authentic tekhelet whereby subjecting the material to a chemical process one can differentiate between authentic tekhelet and imitation tekhelet made from kla ilan.24 The necessity to resort to a chemical test and not just visually ascertain the color with one that is familiar with the authentic tekhelet proves that kla ilan and tekhelet were the exact same color. Kla ilan was invalid for sacramental use not because of its color but because of its source.25

To this end, Rabbi Herzog obtained a sample from the famous Manufacture des Gobelins of authentic indigo which he planned to use as a representative template for the proper color of tekhelet.26 Rabbi Tukachinsky who saw this sample describes it as being “stronger than blue, turning to green, and a little black mixed in”.27 Rabbi Herzog himself remarked that “to the experienced eye a slight reflex of violet or reddish is visible.”28

The problem with this argument is that indigo itself can be found in several color variations ranging from purple29 to violet to blue. Natural indigo can contain up to 15% indirubin (red dye) as well as other impurities that can affect the color of the dye30. Effectively, this proof suffers from the same ambiguity as the linguistic argument that Rabbi Herzog rejected. Since it is unknown to which hue of indigo the Talmud refers we still do not know the true color of tekhelet.

Talmudic Descriptions of Tekhelet

There are several other descriptions of tekhelet which Rabbi Herzog thought corroborated that tekhelet was blue, though he admitted that they are inconclusive. Most famously the Talmud states: “Rabbi Meir used to say; Why is tekhelet so different from all other colorants? For tekhelet is like the sea, and the sea is like the sky, and the sky is like [Lapis lazuli31, and Lapis lazuli is like] the heavenly throne.”32 This statement at first seems to be describing the color of tekhelet, but upon further consideration, Rabbi Herzog contends that the gradations of colors here is actually more of symbolic significance.33 In fact, some versions of this statement expound that the “sea is similar to grass and grass is similar to the sky”34 precluding the understanding that this a simple color gradation. And why was a gradation necessary; was tekhelet itself not similar to sapphire?35 Rabbi Herzog suggests that this long chain of associations was meant to symbolize the similitude of the Throne of Glory throughout the universe.36

Other times it is implied that tekhelet is similar to the dark sky at night. The Talmud writes that the silver hooks in the Tabernacle appeared like shining stars set against the loops made of tekhelet.37 The word tekhelet is also homiletically explicated to be semantically related to the Hebrew word for bereave (תכל), because it was in middle of the night that God smote the Egyptian firstborns.38

Colors in Ancient Times

Throughout his dissertation Rabbi Herzog was quick to note that it is hard to be sure that the colors described in ancient sources are the same colors as we now know them. Not only have the names for the colors shifted along the color scale through history but ancient societies often had a much narrower color vocabulary. Still, Rabbi Herzog believed that the color descriptions were useful to broadly determine that a particularly described item was at least within a certain reasonable range of colors. It is based on this assumption that he analyzes much literature to best determine what the colors of argaman and tekhelet are known as in contemporary times.

Modern anthropologists have pointed out that the issue is actually much more complex. Whereas our own color system is primarily focused on hue, the ancients were sensitive primarily to such things as luminosity, saturation and texture, or even subtler variables such as smell, agitation and liquidity.39 Mark Bradley, a historian of Roman visual art, argues that the ancient sense of color can be described as being somewhat “synaesthetic”, that is to say, they experienced color not just though their visual sense but as an experience that involved multiple sensory systems. For example, color was sometimes used by the ancient Greeks to refer to other sensory experiences such as music’s chromatic scales. Much likes genuine synaesthetes, Greek musicians experienced some correlation of visual and auditory senses when playing music. It was because of this synaesthetic experience that ancients sometimes describe colors in ways which seem very odd to us.

The corollary of this is that when a color is described seemingly inaccurately in ancient sources it is not necessarily because the color scale has shifted or because they had an insufficient vocabulary to accurately describe the color. It might just be that the strange way in which the color is described is the experience that the color evoked or represented in the ancient observers.  Sometimes we may need to look beyond hue to understand what is really being described.

Tekhelet is often described as being similar to the sky and sea.40 Interestingly, the sky and sea are reoccurring motifs in ancient literature. Most famously, Homer in several places describes the sea as being wine-dark (oinops pontos).41 Although there have been attempts to explain how the sea could have appeared red in specific settings,42 Michael Clark, professor of classics in the  National University of Ireland, suggests that it is more likely that Homer’s usage here reflects the conceptual associations of wine, such as danger and frenzy, as well as the whole range of qualities identified with Dionysos.43 Pliny the Elder actually describes the color produced from the purpura, the purple producing Murex snails, in very similar terms when he decries the “mad lust” for the dye. “But what is the cause of the prices paid for purple-shells, which have an unhealthy odour when used for dye and a gloomy tinge in their radiance resembling an angry sea?”44

Homer in three places also describes the sea as the “purple-sea” (alipòrphuros [ali – sea, porphura]). The sea’s color is described as being purple, a reference to the purple color produced by the Murex snails. This description however seems to have more of an actual visual component than the previous term since Homer uses the term porphura which refers to a purple dye. According to Sandra Busatta, a Professor of Social Anthropology at the University of Padua, “To Homer’s audience the word purphureos first referred to the play of the light that produces brilliance on troubled water and by extension any play of sparkling, glossy or shiny color, but it also referred to a negative sense of fear”.45 She suggests that it is for this very reason that Homer described the sky as being bronze, an apparent reference to the glare and sparkling of the metal.46

Arguments for a Violet Tekhelet

Thus far I have shown that the proof presented from the Talmud for the color of tekhelet is inconclusive. Moreover, I have shown that it is difficult to ascertain the hue based off textual evidence from archaic sources since they may be describing the other visual aspects. Furthermore, in this particular case it seems that the Talmudic allusions to the color of tekhelet are describing not its hue but its other visual qualities, namely the shine of fabrics dyed with tekhelet,47 a description of the Murex dye corroborated in many Greek sources. Is there any proof that can be adduced to prove the hue of tekhelet?

There are several arguments that can be made for identifying violet as the color of tekhelet.

First, it must be noted, that without proof to the contrary, the Greek and Latin translations of the Torah that translate tekhelet as hyacinth should be assumed to be referring to the well-known violet colored flower that carries that name. Although the flowers from the hyacinth family may occur in varying colors throughout the world, the dominant species Hyacinthus orientalis L. found in Asia Minor48 is violet. It can be fairly assumed that ancient authors from the Mediterranean are referring to this well-known species.

Secondly, there is a strong argument that tekhelet could not be blue. It is clear from Greek historians that the purple and reddish-purple dyes produced from the Murex snails were extremely expensive. The expensiveness tekhlet is also attested to in the Talmud49 which adds that non-Jews are not to trusted with transporting tekhelet because they are suspected of stealing it and substituting the authentic tekhelet with a fake made of kla ilan (indigo).50 Imitation tekhelet was so rampant that the Talmud requires that one only buy tekhelet from an expert to ensure its authenticity.51 Supporters of blue tekhelet point to this halakhic decree as proof that tekhelet is the same color as indigo. In fact, they claim that molecularly the two dyes are identical. Yet if they were exactly the same, the superiority of the authentic tekhelet is not understood. While Jews can be insistent that tekhelet they use for religious purposes come from the original Biblical dye source, why would the non-Jews prefer the molluscan dye to the molecularly identical plant sourced dye? If anything, we would expect that the blue dye from the indigo plant to be preferred since it did not have a strong fishy smell adhering to it. It wouldn’t make financial sense to use a Murex trunculus for blue dye when it could be used to create the more expensive purple dyes. Although there were fake purple dyes, they were of inferior quality,52 whereas the indigo blue dye was supposedly just as good as the blue tekhelet dye.53 The Talmud’s statement that non-Jews are suspected of substituting authentic tekhelet with imitation tekhelet made of kla ilan clearly suggests that the authentic tekhelet was vastly superior and therefore much more expensive.

The more likely explanation is that the imitation tekhelet made of kla ilan was a mix of indigo and some other red dyes, yielding an imitation violet dye. The Sifrei describes a deceitful person as making fake tekhelet from “pigments” and kla ilan.54 Other sources which refer to imitation tekhelet simply as “kla ilan” possibly did so because indigo was the predominant dye stuff or perhaps the imitation tekhelet was made of indigo from which the red indogotin was not removed.

Perhaps the strongest argument against blue tekhelet is that the debromination process, the process used to convert the Murex dye to a pure blue, would not have been performed in antiquity. The process currently used at the tekhelet factories utilizes synthetic chemicals to reduce the Murex dye to a water-soluble form so that the dye can adhere to the wool. After the dye has been reduced, the debromination is effectuated by exposing the dye to either a UV emitting light or to sunlight for over an hour. In antiquity, a more natural process was required to the reduce the dye to a water-soluble form. Several attempts were made to recreate this process, but it is likely that the ancients utilized the bacteria found in the snail itself to ferment the dyestuff and ready it for dyeing.55

Zvi Koren, the director of The Edelstein Center for the Analysis of Ancient Artifacts, argues that when using the natural fermentation process, it would not have been possible to create a blue dye since this particular fermentation has to be done in an anaerobic environment. Leaving the soluble dye exposed to the sun for considerable time by removing the lid would have caused the dye to return it its insoluble form because of the exposure to oxygen. He argues that the other attempts at natural dyeing were only able to succeed because they used a glass beaker that was sealed and exposed the dye to light without opening it. In ancient times, such glass would not have been used since the dye required large quantities and was heated on a fire for days or weeks.56 The Talmud itself says that the process involved putting the dyestuff into a cauldron and heating it.57

The color of tekhelet might be possible to discern from a comment by Epiphanius of Salamis, one of the church fathers who lived during the 4th century in Israel when tekhelet was still found. Epiphanius, commenting on a passage in Matthew in which Jesus criticizes the Pharisees for making “their phylacteries wide and their craspeda long”58; craspeda being the Aramaic word for Tzitzit. Epiphanius explains that the Greek word phylacteries does not refer to amulets like many believe, but to “purple woven”, which were purple strips woven into clothes in the Greek period.59 The strips to which Epiphanius refers are called clavi. These were strips that the Greeks and Romans used to put on their himations which denoted the rank and prestige of the wearer. It has been proposed that that these clavi are actually the source for the black strips that Ashkenazic Jews print on their tallit and that the tallit itself was originally a himation which the Jews living in lands of predominant Greek culture wore.60 Epiphanius explains that the Pharisees were being haughty by wearing wide clavi which denote a high rank and making their tzitzit long (presumably because the more purple fabric was used, the greater the cost). The very fact that he mentions both together seems to indicate they are of the same color, which he calls purple. Historically clavi, of which there are many existent samples, are purple, thus implying that tekhelet is purple.


Tekhelet was lost over one thousand years ago.  Together with the loss of tekhelet we, as a people, also lost our mimetic tradition of what tekhelet was. Through our written records we preserved many details of what tekhelet is, where it comes from, and what it means to us, but piecing together all of these details after a thousand years in a world vastly changed is tricky business.

In this essay, I showed that what was assumed to be clear Talmudic descriptions of the color hue tekhelet are not necessarily so. Color in the ancient world meant something different than what it means in our modern western society. I attempted to demonstrate that the sea, sky, the lapis lazuli stone, all of which are likened to tekhelet, and even the Murex dye itself, were all chiefly known in the ancient world for their unique shine and glimmer and only secondarily for their hue. When the ancients speak of colors sometimes they intend to convey not how it is visually perceived but how the color is apprehended in the mind and what it represents.

Accordingly, I suggest that if we are to attempt to recreate the biblical tekhelet we should take the ancient biblical translations of tekhelet more seriously, since they are a translation and not a description, and they all unanimously declare tekhelet as violet. I also attempted to show that other proofs identifying tekhelet as blue are unconvincing and that there are several reasons why tekhelet couldn’t be blue.


  1. https://www.opticalexpress.co.uk/magazine/dividing-a-nation-an-insight-into-human-interpretation-through-colour-illusions 

  2. https://en.wikipedia.org/wiki/The_dress_(viral_phenomenon)  

  3. Porphyrology is the study of purple.  

  4. “The Dyeing of Purple in Ancient Israel”, Proceedings of the Belfast Natural History and Philosophical Society 1919-1920 pp. 21-33, reprinted by the Israel Malacological Society and the Municipal Malacological Museum, Nahariya, 1981. See also Ir haKodesh v’haMikdash, vol. 5, p. 56, where he is quoted in a letter as saying, “And in regard to the exact color of tekhelet, I expanded and studied it as far as my hand can reach, and I am without doubt.” 

  5. “ha’Hillazon Shel Tekhelet al pi haHakirot ha’Archiologiot b’Siyua Nisyonot Ma’assiyim.” Ha’Hed, 12 (1934), p. 17.  

  6. Rabbi Herzog mentions in a letter to Rabbi Yechiel Michel Tukachinsky that he plans to conduct tests on the coast of Haifa to validate the “secret of the tekhelet snail” that he thinks he has uncovered. See Ir haKodesh v’haMikdash, ibid p. 57.  

  7. I find this strange because already in 1810, The Belfast Monthly Magazine reported that the dye of a similar Buccmum snail was extremely colorfast. See “On the Tyrian, or Purple Dye”, The Belfast Monthly Magazine, 1810, 5 (25), pp. 93-95, available at <https://archive.org/details/jstor-30072679>. 

  8. ha’Hillazon Shel Tekhelet, ibid. Many of the supporters of the Murex tekhelet deceitfully tell a different narrative where R’ Herzog biggest problem was with the dye not being completely blue. See for example, Baruch Sterman, The Rarest Blue, p. 130, “The primary argument against the trunculus, however, was the color. Tekhelet had to be sky blue. This was a long held Jewish tradition that Rabbi Herzog could not dismiss—but the blue obtained from the Murex trunculus appeared blueish purple.” Even Gadi Sagiv who wrote an article to expose some the fallaciousness of the Ptil Tekhelet narrative seems to embrace this falsity. See “Deep Blue: Notes on the Jewish Snail Fight”, Contemporary Jewry, 35:3 (October 2015), p. 290.  

  9. ha’Hillazon Shel Tekhelet ibid. This belief is based on what he heard from Lacaz Duthiers who claims to have encountered through his experiments a murex trunculus which yielded a blue dye but at other times was violet. See Semitic Porphyrology (manuscript edition) p. 133. Rabbi Herzog also mentions the possibility of somehow removing the red elements from the murex dye. 

  10. L. A. Driessen, “Über eine charakteristische Reaktion des antiken Purpurs auf der Faser”, Melliand Textilberichte, 1944, v. 25, pp. 66-69; J Van Alphen, “Remarks on the Action of Light on several substances, most of them containing halogen, in particular several Indigo Dyes, in a Reducing Medium”, Recueil des travaux chimiques des Pays-Bas, 1944, v. 63, pp. 95-96. Sterman includes both of the above citations in his bibliography but in his book, he inexplicably attributes the rediscovery of the blue dyeing process to Otto Elsner who independently rediscovered the method serendipitously by accidently exposing the dye to light in 1985 (p. 134). Sagiv, Deep Blue, p. 292, points that Elsner himself explicitly stated that this result was based on a study conducted by two German scientists. 

  11. The Rarest Blue p. 207.  

  12. Sky-blue is the color of the sky at noon. Sterman even claims that this was the view of Rabbi Herzog in an article in BAR. See “The Great Tekhelet Debate—Blue or Purple?”, BAR, 39:05 (September/October 2013). This is in contradiction to Rabbi Herzog own expressed opinion that is was “deep dark blue”. 

  13. For example, Pesikta Rabati (circa 9th century), piska 20 (matan Torah) Ish Shalom edition.  

  14. Ex. 35:23,25; Ezekiel 27:24 

  15. Ex. 35:23; Ezekiel 23:6 

  16. Ex. 28:6, 35:23,25; Jeremiah 10:9; Ezekiel 23:6 

  17. Ex. 25:4, 26:1,31,36, 27:16, 28:5,6,8,15,33, 35:6,24,26; 36:37, 38:18,23, 39:1,2,8,22 Ezekiel 23:6, 27:7 

  18. Alternatively, ὑακίνθινος. 

  19. Jerome uses ianthinum (violet) in translation of תחש. This should probably be understood as the same as hyacinthum because his rendering of tahash is dependent on the LXX which renders tahash the same as tekhelet. 

  20. Antiquities 3:8; Wars 6:6  

  21. de Vita Mosis 3:2 

  22. Herzog, Semitic Porphyrology, p. 93-94, 161, (manuscript edition)  

  23. This is the proof Rabbi Herzog cited when pressed by Rabbi Yechiel Michel Tukachinsky to provide a definitive proof for the exact color of tekhelet. See Ir haKodesh v’haMikdash, ibid p. 59. 

  24. Menahot 42b 

  25. Tosefta Menahot 9:6 

  26. Ir haKodesh v’haMikdash idem. It is unclear to me if this was an actual swatch of indigo or a photograph of a swatch. He uses the word “temunah” but it is unclear if he intends it to mean a colored sample. If he had meant photograph at the time he showed it to Rabbi Tukachinsky it was over 40 years old and it would be unreasonable for him to use this as a source because it can be assumed that the color had faded and color reproduction in photographs at the time was not very accurate in the first place. 

  27. Idem. It seems to me that Rabbi Tukachinsky’s remarks are not objective observations about the color he saw but are rather his comments that the color he saw confirmed his expectations he had based on his prior research. 

  28. Herzog, Semitic Porphyrology, p. 217 

  29. Ctesias seems to be referring to the indigo plant when he says, “Near the sources of this river there grows a certain purple flower, which is used for dyeing purple, and it is not inferior to the Greek sort, but even imparts a more florid hue.” Ctesias makes no other mention of indigo, one of the prominent Indian exports at the time, and there is no known flower from India that can be used for dyeing purple. It therefore seems reasonable to assume that Ctesias is referring to the indigo plant.  See Ancient India as described by Ktêsias the Knidia, translated by J. W. McCrindle, (London 1882) p. 22. Pliny also describes indigo as producing a mixture of purple and blue. He also mentions the existence of “scum of purple” which ostensibly produced some type of purple dye. See Natural History, Book XXXV, Ch. XXVII, §46, translated H. Rackham, W.H.S. Jones, D.E. Eichholz, (Harvard University Press, 1949-54).  

  30. J. Merritt Matthews, Application of Dyestuffs to Textiles, Paper, Leather and Other Materials, (John Wiley & Sons, Inc., 1920), p. 410fn. Indirubin is reduced to a leuco in the same way as indigo though the reduction is slower. Dyers without knowledge of how to chemically remove the indirubin may see varying amounts of indirubin in the dyed fabric depending on the efficiency of the reduction agent and the length of the reduction process.

    A friend of mine that is involved with the promotion tekhelet attempted to recreate a natural indigo dye so that he could subject the fabric to the tests the Talmud gives for the differentiation of authentic tekhelet and indigo (Menahot 42b). He theorized that although the molecular structure of tekhelet and indigo were the same and they are both vat dyes, perhaps, in antiquity the reduction process for the dyes differed and that is why it was possible to differentiate between them with a chemical test. However, his attempt to create a natural indigo dye resulted in a purple fabric. He later tested an ancient indigo sample and supposedly found his theory to be true. See also Meir Hellman, Levush HaAron, pp. 68-70.

    Incidentally, I should note that this theory is probably correct because historically indigo was not necessarily used as a vat dye but as a mordant dye. Pliny, for example only mentions it use in painting and says that when mixed with water it creates a beautiful purple and blue which is not how it appears when vat dyeing. This is particularly true when indigo was used in conjunction with another red dye to create an imitation purple which necessitates a mordant for dyeing. See R. J. H. Clark et all, “Indigo, Woad, and Tyrian Purple: Important Vat Dyes from Antiquity to the Present”, Endeavour, 17:4 (1993), p. 191. See also footnote 53 below.

    Indigo was exported from India as dried blocks and looked like a black clump before being dissolved in water. It is possible that the name for indigo in the Talmud is on account of this קלא – burnt אילן – tree, a description of what the item appeared to be. Being an imported item it is not surprising its exact source was not known, Pliny also has a mistaken understanding of the indigo plant (Book XXXV Ch. XXVII). I find this etymology more likely than the Sanskrit suggestion of Herzog or the identification with callanium (Καλλαιλαν).  

  31. Missing in some texts. The Hebrew word ספיר is often translated as sapphire but sapphire in ancient text most often refers not to the modern gem known under that name but to Lapis lazuli. See Theophrastus on Stones, E. R. Caley & J. C. Richards, Ohio State University Press (1956), p. 136. Theophrastus (30) says there were two types of Lapis lazuli stones, a male and a female, the former being the darker variety. The stone’s color can range from deep violet blue and royal blue to light blue to turquoise blue to a greenish blue. The stone most often contains specks of gold-colored pyrite giving the appearance of a midnight sky with sparkling stars. It is probably this similarity to the midnight sky that is referred to here. Pliny (Book XXXVII Ch. XXXIX) writes that most Lapis lazuli are blue and only rarely are they tinged with purple. Epiphanius writes the sapphire of the breastplate was royal purple colored. However, in an epitome of the work it is described as “crimson purple, like to the red sheen of black velvet is its appearance” but it is later stated “They say that there is also a blue one like lapis lazuli”. See Epiphanius de Gemmis: The Old Georgian Version and the Fragments of the Armenian Version, R. P. Blake, Christophers, London (1934), p. 133, 201 Epitome B.

    Based on the above I find it inconsequential to this debate that the Sumarian cognate for tekhelet was also the word used for Lapis lazuli and things of that color. Lapis lazuli occurs is both blue and violet shades and probably served as a name for both colors. See Benjamin Rusch, “’Biblical Blue’ Tekhelet (תכלת) Ecclesiastical Dye and its Archaeological Identity in the Ancient Near East”, pp. 3-4. https://www.academia.edu/15286548/Biblical_Blue_Tekhelet%D7%AA%D7%9B%D7%9C%D7%AA_Ecclesiastical_Dye_and_its_Archaelogical_Identity_in_the_Ancient_Near_East [accessed 64/17] Sandra Bussata explains that in Sumerian “uqnu was used to describe dark blue, dark purple and even black materials, but with associated notions of brilliance and splendor, reflecting the value of lapis lazuli in the ancient Near East because of its rarity and attractive luster, augmented by small traces of silvery pyrite and white calcite in the dark blue matrix, which gives the material a glittering quality perhaps connected to the night sky.” See her essay, “The Perception of Color and The Meaning of Brilliance Among Archaic and Ancient Populations and Its Reflections on Language”, Antrocom Online Journal of Anthropology, 10:2 (2014), p. 325 

  32. Menahot 43b, Sotah 17a, Ḥulin 89a 

  33. Herzog, Semitic Porphyrology, p. 206, (manuscript edition). “R. Meir’s object in this instance, be it duly emphasized, is not to give a definition of tekelet but merely to explain its symbolic significance.” 

  34. Jerusalem Talmud, Berachot 7b. Rabbi Herzog himself suggests that it still could be color gradations and the “grasses” referred to are blue types of greenery such as the hyacinth flower. See Semitic Porphyrology, p. 212. 

  35. Mishnat Rabbi Eliezer, ch. 14 states, “tekhelet resembles Lapis lazuli, and the Tablets were of Lapis lazuli, to tell you that so long as the people of Israel gaze upon this tekhelet they are reminded of that which is inscribed on the Tablets and they fulfill it.”  

  36. Semitic Porphyrology, ibid. 

  37. Shabbat 99a. 

  38. Sifrei, Parshat Shelah. See the explanation of R’ Moshe HaDarshan cited by Rashi in Bamidbar 15:41 s.v. ptil tekhelet. 

  39. Mark Bradley, “Colour as Synaesthetic Experience in Antiquity.” Synaesthesia and the Ancient Senses, edited by Shane Butler and Alex Purves, Acumen Publishing, 2013, p. 127  

  40. Rabbi Meir above in footnote 31. See also Josephus, Antiquities of the Jews, Book III, 7:7, where tekhelet is compared to the sky and the air. Cf. Midrash Raba Bamidbar, 4:13.  

  41. Iliad 23.143; Odyssey 5.132; 5.221; 7.250; 12.388  

  42. See the literature cited by Bradley, Colour as Synaesthetic, on pp. 132-133. 

  43. Michael Clark, “The Semantics of Colour in the Early Greek Word-Hoard”, Colour in the Ancient Mediterranean World, ed. Liza Cleland and Karen Stears with Glenys Davies, pp. 131-139; Oxford; 2004. Clarke in fact suggests that the Greek word for purple, πορούρεος, is rooted in this association with the sea which can be described as heaving and surging. “Diachronically the word seems to have been conflated from two distinct sources, the reduplicated verb πορφορω ‘heave, surge’ and the name of the purple murex, πορφορα.” (footnote 32). For the symbolic meaning of colors in antiquity see Frederic Portal, An Essay on Symbolic Colors: In Antiquity, the Middle Ages, and Modern Times, trans. W. S. Inman, London, 1985.  

  44. Pliny the Elder, Natural History, Book IX, Ch. LX. 

  45. Sandra Busatta, The Perception of Color, p. 316.  

  46. Iliad 5.504, 17.424-5; Busatta, idem. The early Greeks believed that the sky was a sort of hemispherical dome made of metal that covered the earth, a view that is also found Rabbinic literature. See Natan Slifkin, The Sun’s Path at Night <http://www.zootorah.com/RationalistJudaism/TheSunsPathAtNight.pdf> 

  47. Mark Bradley, writes that the purple sea dye “had unique physical properties, sitting on the surface of garments rather than within the fabric and reflecting and manipulating sunlight in a similar fashion to oil floating on water.” See “The Colour Purple in Ancient Rome”, p. 12-13 <http://www.saturatedspace.org/2014/05/the-colour-purple-in-ancient-rome.html>.  

  48. See A. Horovitz & A. Danin, “Relatives of Ornamental Plants in The Flora of Israel”, Israel Journal of Botany, 32:2 (1983), p. 91. The Hyacinthus orientalis is indigenous to Israel where it commonly grows wildly on the limestone rock in the Upper Galilee.  See http://flora.org.il/en/plants/hyaori/. Hyacinthella nervosa is also native to Israel and its flowers are similarly violet colored. http://flora.org.il/en/plants/HYANER/  

  49. Menahot 44a 

  50. Avoda Zara 39a 

  51. Menahot 42b 

  52. Pliny discusses the quality of different purples at length. 

  53. In footnote 30 I surmise that the ability to use indigo as a vat dye may not have been well known. There is however evidence that indigo was used for vat dyeing in the Stockholm Papyrus (recipe 105) which has directions for dyeing with indigo by using fermented urine which is a reduction agent. It is possible that this method of dyeing was known at the time of the composition (CE 300) and in the local (Eygpt) but not at the time of Pliny. It has been suggested that the Greeks and Romans had a particular disdain for the color blue and perhaps this contributed to the indigo dyeing methods not being well known. See Bussata, The Perception of Color, pp. 334-6. The kela ilan of the Talmud was probably a vat dye based of the prescribed tests (Menahot 42b)  

  54. Sifrei, Parshat Shelah 73  

  55. See the history and citations in, Zvi Koren, “The First Optimal All-Murex All-Natural Purple Dyeing in the Eastern Mediterranean in a Millennium and a Half”, Dyes in History and Archaeology (20), Archetype Publications, London, pp. 139-140. Koren thinks that the use of a chemical reduction agent, even a natural substance such as tin is unlikely to have been used in antiquity. I personally do not find all of his arguments convincing. I believe that a chemical reduction agent was not historically used because the preparation process as recorded in ancient required several weeks. Had they used a chemical agent the process would have only taken several hours.  

  56. Zvi Koren, “New Chemical Insights into the Ancient Molluskan Purple Dyeing Process”, Archaeological Chemistry VIII, ed. R. A. Armitage & J. H. Burton, ACS Symposium Series 1147, American Chemical Society: Washington DC; Chapter 3, pp. 51-52. See also his response to Sterman in BAR http://www.biblicalarchaeology.org/daily/biblical-artifacts/artifacts-and-the-bible/zvi-c-korens-reply-to-the-stermans-response/ . Koren also dismisses Roy Hoffman’s attempts, who besides using a glass vessel that was covered, also only received blue after a second dyeing in the same dye bath. Koren has shown that the red dibromoindigo (DBI) has a higher affinity to wool than the blue indigo (IND) and in the first dyeing DBI will adhere to the wool more readily than IND, see Koren, The First Optimal, p. 143. The second dyeing resulting in a bluer wool is explicitly disqualified in the Talmud (Menahot 42b). Based on Koren’s finding we can perhaps suggest that this is another indication that the desired color of tekhelet was violet (Cf. Rashi and Tosfot in Menahot ibid). Hoffman himself admits that natural blue dyeing was probably impossible on a commercial scale, thereby conceding that the dyeing process described in the Greek authors was not for a blue dye. See Roy Hoffman, “The Identity of Tekhelet: New Findings” (Hebrew), Bekhol Derakhekha Daehu (BDD), 27 (March 2013), p. 17.  

  57. Menahot ibid 

  58. Matthew 23:5. Craspeda appears in the Greek version.  

  59. The Panarion of Epiphanius of Salamis: Book I (Sects 1-46), tran. Frank Williams, Brill (2009), Ch. 15 1.4, p. 41-42 

  60. See Erwin Goodenough, Jewish Symbols in the Greco-Roman Period. Volume Nine: Symbolism in the Dura Synagogue, p. 171 -174. For clavi as the source of the black strips on the tallit see Daniel Sperber, Minhagei Yisrael, vol. 5, Mossad HaRav Kook (1995), pp. 207 n. 5. Traditional sources suppose that the strips on the tallit were a remembrance for tekhelet and originally the tekhelet and the tallit strips were the same blue color. See R. Joseph Teomim, Pri Megadim to Shulhan Arukh, O.H., ch. 9, Eshel Avraham, no. 6.  

About Efraim Vaynman

Efraim Vaynman is an Editorial Intern at Torah Musings. He is a rabbinical student at Yeshiva University’s Rabbi Isaac Elchanan Theological Seminary while concurrently pursuing an MA in Talmud at the Bernard Revel Graduate School of Jewish Studies. Previously, Efraim studied in yeshivot Brisk and Beth Medrash Gevoha.


  1. Efraim Vaynman

    Let me just preempt an issue I think some people will raise. What about the archeological evidence? Did they not find fragments of tekhelet in Israel that are blue?

    Zvi Koren and Naama Sukenik both have found blue textile fragments from the Judaean Desert that they confirmed through chemical testing to be from the Murex trunculus. However, neither of these fragments were sky-blue. Koren describes the bluest fragment he found as midnight blue, while Sukenik described her fragment as “greenish-blue” and her fragment is rather dark.

    It is possible to obtain bluer hues from the Murex trunculus without subjecting the dye to photodebromination. Some Murex trunculus snails (typically younger smaller ones) naturally have more indigo than others and can produce deep blue dyes such as the midnight blue fragment of Koren. It is even possible to obtain a sky-blue color from the Murex without using any synthetic chemicals at all. Deborah Ruscillo has found that by steeping wool directly in the Murex’s dye immediately after it is extracted it is possible to direct dye with it. After letting the wool dry in the sun, she found that it turned blue and this blue did not fade or wash out. This method works because evidently the dye is still in a soluble form after being extracted and will therefore bind to the wool and be subject to photodebromination. (See her article Reconstructing Murex Royal Purple and Biblical Blue in the Aegean.)

    I am not disputing that it is possible to obtain blue colors from the Murex trunculus. My argument is: 1. That there is no conclusive evidence that tekhelet was blue. 2. I think the strongest sources seem to identify it with the color of the hyacinth flower which is more violet like. 3. There is good reason to believe that it probably was not sky-blue. Not because it was technically impossible to obtain a sky-blue dye in antiquity but because it was unlikely and did not correspond to the dyeing methods described in the Talmud.

    Still, it is possible that sky-blue tekhelet is kosher for the mitzvah. Tekhelet is undoubtingly a range of colors. Where it starts and ends on the color scale is impossible to say. I am only arguing that the primary color was more of a violet hue. Perhaps a sky-blue hue is also called tekhelet. You might even argue that it is likely since in biblical Hebrew there does not seem to be another name for such a color and tekhelet is probably next closest color.

  2. If tekhelet is violet, then what is argaman? (As I understand it, the “commonly held” belief is that tekhelet is blue and argaman is purple, and the proponents of the murex snail explain that the different names are for the two possible hues.)

    • Efraim Vaynman

      I still believe that argaman was purple. However, purple in older texts, particularly the Greek texts, was actually much more reddish. Argaman was a reddish purple and and tekhelet was a blueish purple.

      • Do you agree that both tekhelet and argaman came from murex snails? If so, how did they control the color when dyeing to get a specific one? Was it just a surprise every time?? (I may be misunderstanding, but I thought from your article that you are disputing how well they could reliably use sunlight to change the color of the murex dye, so they’d [almost] always get somewhat of a violet/purple-ish color.)

        Can you elaborate on the connection between argaman and the Greek “purple” and how you know that is a reddish-purple (eg. is there some flower of known color it is compared to, like the hyacinth is to tekhelet)?

        (I know this may seem like a separate discussion, but I feel you can’t argue tekhelet=violet without dealing with how that affects argaman, because if we don’t have an answer to that, we’re left with a strong question on your argument.)

        • Efraim Vaynman

          Yes, both argaman and tekhelet came from Murex snails. The Septuagint translates argaman as porphura which is the Greek name for the Murex family of snails. This translation is also found in the other translations such as Aquila as well as Josephus and Philo. (Though Rambam and some others believe it be from an insect source.)

          The porphura is well attested to in Greek sources. Various shades were produced from the snails including the hyacinthine subtype which is the biblical tekhelet. However, the main color produced from the porphura was called blatta, which is the Greek word for blood and resembled congealed blood somewhat like the bordeaux color. Jewish sources too say that argaman was a reddish color and recently a book was authored collecting all of these sources. See Yisroel Rosenberg, Kuntres Merkavo Argaman, available here.

          As for controlling color, this was probably very difficult. Researchers have found that the young and smaller Murex trunculus snails contain a bluer dye but there are other factors which affect the dye color as well such as the region, season, or the sex of the snail. The differences may have been known to the ancients and it is possible that they were so attuned that they could consistently produce certain colors based on these signs.

          The Murex haemastoma and Murex brandaris both produce reddish-purple dyes. Previously it was thought that these snails were the source of argaman and the Murex trunculus was the source of tekhelet. However, it has been shown that the haemastoma and brandaris will not produce purple dyes unless some trunculus dye is used. Koren has analyzed many examples of ancient molluscan purple textiles and has always found that they contain MBI which can only be found in the trunculus. We must therefore conclude that argaman and tekhelet are just two shades of the porphura snails. If so, perhaps there was no consistent way to produce either color and the determination of tekhelt or argaman was based on the end color obtained.

  3. The gemara divides the domain described as “yaroq” between “yaroq kekarti” (yaroq like a leek) and “yarok kekarkom (yaroq like saffron). Clearly a wide swath. But what then do they mean by yaroq, if not the range of hues running from a leek’s dark green to the yellow, almost orange, of saffron? Basically everything between kachol and adom. The two have little to nothing in common in texture or sheen.

    For that matter, it’s notable that color in leshon tanakh comes in adom, yaroq and kachol, when not speaking of specific dyes of specific substances — like tekheiles. (Which is not a dye, but wool colored by a particular dye.) It would be coincidental if the language had terms corresponding to the primary colors, but didn’t discuss our notion of hue-saturation-luminosity.

    As to what color tekheiles would have… There is a machloqes whether the earliest time for tzitzis is when we there is enough sunlight to distinguish between the tekheiles string(s) and the whiite ones (tana qama), or between tekheiles and karti (R’ Eliezer). It would seem that R’ Eliezer is demanding something significantly different than enough light to distinguish between white (or the off-white of unbleached woolen strings) and tekheiles. Leeks are a dark green, and I would think the implication from R’ Eliezer is that tekheiles is similar in saturation and luminosity. In other words, the tana qama’s criterion can be satisfied with enough light for the rods in our retinas can determine luminosity, but R’ Eliezer requires our cones functioning well enough to distinguish hues. Measurably later.

    If tekheiles does refer to violet, R’ Eliezer’s opinion is much closer to the tana qama’s.

    But again the comparison of yaroq kekarti and tekheiles is of color as we use the word in modern English.

    And this is consistent with the comparison to lapis lazuli or to sapphire, or even to the blue streaks in blue marble. None of the stones suggested for the lukhot is colored violet. For that matter, it’s the same word, ספיר, that’s compared to the color of the sky (“ותחת רגליו כמעשה לבנת הספיר וכעצם השמים לטהר” -Shemos 24:10) — which really only comes in violet in a small streak for a couple of minutes in a perfect sunrise or sunset (when much of the spectrum is present). Is the comparison to the texture or shininess of the sky — what would that even mean?

    I would therefore presume that tekheiles, being the color of sapphire, which matches the clear/pure sky, has to be some shade of blue, depending on the time of day. The notion of sky blue is a pretty straightforward take of its comparison to something כעצם השמים לטהר.

    (I would also argue that given the notion of being pure like the sky, the implication is that ספיר is indeed a translucent stone, and not any of the more recent suggestions. But that’s a tangential discussion.)

    • Efraim Vaynman

      There is no blue in Tanakh. כחל that appears once means a dark pigment for the eye. The כחול of modern Hebrew is due to the influence of Arabic and doesn’t appear until much later. Even Rambam when talking about tekhelet is not using it in the sense of blue (see Zohar Amar in HaArgaman). The blue color was probably either considered ירוק or תכלת.

      Hebrew, like some other ancient languages, does not have a word for blue. Blue is a rare color in nature and for some reason some ancient civilizations didn’t develop a word for this. Research on remote African tribes has shown that they have trouble distinguishing between colors which have no linguistic correlation in their native langue. In tests, they are slower to distinguish between these colors and are more prone to mistakes. I suppose that a similar phenomenon is at play in the Mishna in Brakhot.

      The notion that the sky is blue is very much dependent on having the linguistic capacity to define it. If blue has no word, or if the color blue is not commonly used, the sky might be described by its other visual aspects. If it were described in a certain way in the early history of the civilization that description might persist even as blue becomes more common in the language. (For the history of blue and particularly the description of the sky as blue see, Guy Deutscher, Through the Language Glass: Why the World Looks Different in Other Languages, ch. 3, pp. 58-77.) In particular to the explanation of כעצם השמים לטהר, this refers to, in my opinion, the purity of the sky, i.e. the one uninterrupted color. That is to say, the verse describes God’s throne as similar to Lapis lazuli, but unlike Lapis there are not glittering pieces in the middle but it is rather pure like the middle of the sky which is monochromatic. (Incidentally, Theophrastus uses the word kyanos to refer to a Lapis lazuli of a solid color or at least one with drastically less pyrites that were not as noticeable.)

      • But both the examples I brought from the gemara and the comparison of a dyed thread to lapis lazuli (or any other candidate ספיר) clearly are talking about the color (in the current sense of the word) of tekheiles, and thus are saying the color of the string differs only from that of leeks by hue, or that the hue-saturation-luminosity triplet of the string is the feature of the surface what is similar to that of the stone. The stone has no other features in common with the illusory surface of a clear sky. I am questioning your dismissal of these comparisons as referring to different aspects of the surface, when it doesn’t fit with how either Tanakh or Chazal understood the concepts in our cases.

        • Efraim Vaynman

          I think you may have misunderstood the theory I am suggesting. I am not saying hue was never independently considered. Sometimes it is possible to tell from the context that the discussion surrounds only hue. In context of the statements about tekhelet the similarity between tekhelet and the sky or Lapis lazuli is not (only) hue. In footnote 31, I mention that the similarity of tekhelet and Lapis lazuli was the shared luster they both exhibit. Additionally, in the context of Rabbi Meir’s statement about the sky being similar to Lapis lazuli there might be another similarity of the pyrite bits of the Lapis lazuli that look like stars in the sky.

          To restate this in a different way, consider that in the mind of the ancients irradiance/darkness/shininess/dullness was the main focal component of vision and hue of only secondary importance. Compound that with fact that the color hue palette was simple and loosely defined and hopefully you can now understand why in the minds of some of the ancients the striking similarity between different items was the way that these things reflect on the eye and not just their hue which may be off by a bit. Another important point to keep in mind is that the sky, indigo, and Lapis lazuli all naturally occur in violet colors at times. This may have conceptually impacted the types of similar associations that made in their minds.

          • If I understand correctly, you are saying that when tekheiles and lapis lazuli (an identification not any more sure than our original question) are compared, it doesn’t refer to hue. Nor when lapis lazuli and the sky.

            Perhaps it would help if you could explain what a piece of blue wool and a stone do share in common that would be the plausible alternative? Or that stone and the sky?

            And would you not say that Rabbi Eliezer’s definition of mishayaqir implies that tekheles and leeks are similar in saturation and luminosity? Isn’t is hue in particular that our eyes require more light to determine, and so if R Eliezer meant something else, his position was pragmatically pretty much the same thing as the tana qama’s?

            Similarly, how do we understand the conversations about mar’os, or various whiteness

            And if there are colors of adom (which included at least blood-red and dirt-brown) and yaroq (ranging from saffron-gold to leek-green), how can we say our own culture didn’t define color as ranges of hues? What about when chazal talk about the whiteness of a nega, or the color of a mar’eh?

            In short, you reiterate this point of the original post, but did not spell out how my questions reflect misunderstanding rather than simple disagreement.

            • Efraim Vaynman

              I was under the impression that you asked your questions looking for an answer. If you don’t want to accept my theory, fine, just state so. I think the theory I have proposed answers the questions you repeatedly ask. As it happens, it is clear from your comment that you have not fully understood. I did not say that the comparisons don’t refer to hue. I said that hue was of secondary importance, which practically means that if the other visual aspects are similar, then if the hue is slightly off the ancients would still make associations between the items.

              As for your other places in halacha that discuss color, I believe that in some places it is actually evident that what is being discussed may not be hue. I never said that our culture didn’t define color as ranges of hues; I actually wrote the exact opposite. Our western society has trouble discussing colors without narrowly defining them as a range of hues. When it comes to ancient texts we must be open to the idea that color meant more than just a hue. It was a singular experience made up for various visual components which were not described in individual abstract terms but by comparisons to other items. The intention of these comparisons if often lost on westerners that refuse to think outside of the box.

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