Tekhelet
Tekhelet is a "blue-violet", "blue", or "turquoise" dye highly prized by ancient Mediterranean civilizations and mentioned 49 times in the Hebrew Bible/Tanakh. It was used in the clothing of the High Priest, the tapestries in the Tabernacle, and the tzitzit affixed to the corners of one's four-cornered garments, including the tallit.
Tekhelet dye was critical for the production of certain articles in the Jerusalem Temple, as well as for the commandment of tzitzit. Tekhelet is most notably mentioned in the third paragraph of the Shema, quoting. However, neither the source nor method of production of Tekhelet is specified in the Bible, but according to the Tosefta the Ḥillazon is the exclusive source of the dye. The Talmud further informs us that the dye of Tekhelet was produced from a marine creature known as the Ḥillazon.
A garment with tzitzit has four tassels, each containing four strings. There are three opinions in Rabbinic literature as to how many of the four strings should be dyed with tekhelet: two strings; one string; or one-half string. Knowledge of how to produce tekhelet was lost in medieval times, and since then tzitzit did not include tekhelet. However, in modern times, many Jews believe they have identified the Ḥillazon and rediscovered tekhelet manufacture process, and now wear tzitzit which include the resulting blue dye.
Biblical references
Of the 49 or 48 uses in the Masoretic Text, one refers to fringes on cornered garments of the whole nation of Israel, 44 refer to the priesthood or temple clothes and garments. The remaining 6 in Esther, Jeremiah and Ezekiel are secular uses; such as when Mordechai puts on "blue and white" "royal clothing" in Esther. The color could be used in combination with other colors such as 2 Chronicles where the veil of Solomon's Temple is made of blue-violet, purple and scarlet. may indicate the source of the shellfish to have been the Aegean region. In addition to the above observations it should be added that all of the instances of tekhelet attribute its usage to some kind of elite. From this perspective it becomes obvious that it was difficult to obtain and expensive what is further corroborated by the later rabbinic writings.History
At some point following the Roman destruction of the Second Temple, the actual identity of the source of the dye was lost, and during a period of over 1,400 years, most Jews have only worn plain white tassles.The stripes on prayer shawls, often black, but also blue or purple, are believed by many to symbolize what the lost Tekhelet which is referred to by various sources as being "black as midnight", "blue as the midday sky", and even purple. These stripes of tekhelet inspired the design of the flag of Israel.
Identifying the color of ''tekhelet''
Despite the general agreement of the most of the modern English translations of the phrase, the term tekhelet itself presents several basic problems. First of all, it remains unclear to what extent the word in biblical times denoted an abstract color or the actual source material. This problem is specific neither for the tekhelet nor for the biblical Hebrew and the scholars often point to other languages which feature similar phenomena. Second, although with time it came to denote the color blue solely, the exact hue in the Antiquity remains unknown. Basing on the scarce material evidence from the ancient Near East and the early biblical translations the scholars suppose that tekhelet probably belonged to the spectrum between blue, red and purple.In the Septuagint, tekhelet was translated into Greek as hyakinthos. The color of the hyacinth flower ranges from violet blue to a bluish purple.
The early rabbinic literature in turn provide two main expositions for the color of techelet. One group of sources, including Bava Metziya 61a-b and Menachot 40a-b, mentions qala ilan, an indigo dye described as visually indistinguishable from tekhelet. Yet, although this dye was much cheaper to obtain, the rabbis cursed those who substituted techelet with some low-priced equivalent and in fact preferred to annul the obligation altogether rather than to compromise its value, which clearly proves that it was not the color which mattered most. The second and much more numerous group compares the tekhelet to the color of the sky or the sea which is not far off from indigo. More importantly, however, this group contains several instances which extend the comparison and liken the tekhelet to the throne of glory. Apparently, the particular features of this divine chair are not speculated in the ERL, but it can be safely assumed that, again, these were not the visual qualities which counted here but rather the extraordinary value of the object and its explicit cultic associations.
Rashi describes the color of tekhelet as “poireau,” the French word for leek, transliterated into Hebrew.
In conclusion, its color varies between central sky blue in sunlight, through the iris indigo of the rainbow to deep African violet in dull weather; translated in a German translation of the biblical book of Exodus, as "blauem purpur".
Identifying the ''ḥillazon''
Various sea creatures have been suggested as the ḥillazon, the purported source of the blue dye.''Hexaplex trunculus''
In his doctoral thesis on the subject, Rabbi Yitzhak HaLevi Herzog named Hexaplex trunculus as the most likely candidate for the dye's source. Though Hexaplex trunculus fulfilled many of the Talmudic criteria, Rabbi Herzog's inability to consistently obtain blue dye from the snail precluded him from declaring it to be the dye source.According to Zvi Koren, a professor of chemistry, Tekhelet was close in color to midnight blue. This conclusion was reached based on the chemical analysis of a 2000-year old patch of dyed fabric recovered from Masada in the 1960s. The sample, shown to have been dyed with Murex snail extraction, is a midnight blue with a purplish hue.
Additionally, in 2013, Na'ama Sukenik of the Israel Antiquities Authority verified a 1st-century CE-dated fragment of blue-dyed fabric to have used H. trunculus as the source of its pure blue color.
In the 1980s, Otto Elsner, a chemist from the Shenkar College of Fibers in Israel, discovered that if a solution of the dye was exposed to ultraviolet rays, such as from sunlight, blue instead of purple was consistently produced.
In 1988, Rabbi Eliyahu Tavger dyed Tekhelet from H. trunculus for the Mitzvah of Tzitzit for the first time in recent history.
Based on this work, four years later, the Ptil Tekhelet Organization was founded to educate about the dye production process, and to make the dye available for all who desire to use it. The television show The Naked Archaeologist interviews an Israeli scientist who also makes the claim that this mollusk is the correct animal. A demonstration of the production of the blue dye using sunlight to produce the blue color is shown. The dye is extracted from the hypobranchial gland of Hexaplex trunculus snails.
Chemically, exposure to sunlight turns the red 6,6'-dibromoindigo in snails into a mixture of blue indigo dye and blue-purple 6-bromoindigo. The leuco solution form of dibromoindigo loses some bromines in the ultraviolet radiation.
''Sepia officinalis''
In 1887, Grand Rabbi Gershon Henoch Leiner, the Radziner Rebbe, researched the subject and concluded that Sepia officinalis met many of the criteria. Within a year, Radziner chassidim began wearing Tzitzit that included threads dyed with a colorant produced from this cephalopod. Some Breslov Hasidim also adopted this custom due to Rebbi Nachman of Breslov's pronouncement on the great importance of wearing Tekhelet and in emulation of Rabbi Avraham ben Nachram of Tulchyn, a prominent Breslov teacher who accepted the view of his contemporary, the Radziner Rebbe.Rabbi Herzog obtained a sample of this dye and had it chemically analyzed. The chemists concluded that it was a well-known synthetic dye "Prussian blue" made by reacting Iron sulfate with an organic material. In this case, the cuttlefish only supplied the organic material which could have as easily been supplied from a vast array of organic sources. R. Herzog thus rejected the cuttlefish as the Ḥillazon and some suggest that had the Grand Rabbi Gershon Henoch Leiner known this fact, he too would have rejected it based on his explicit criterion that the blue color must come from the animal and that all other additives are permitted solely to aid the color in adhering to the wool.