Rediscovered, Ancient Color Is Reclaiming Israeli InterestAn earlier effort to recover tekhelet dye is also mentioned in the article and was noted here at PaleoJudaica in 2003.
By DINA KRAFT (NYT)
Published: February 27, 2011
RAMAT GAN, Israel — One of the mysteries that scholars have puzzled over for centuries is the exact shade of blue represented by “tekhelet,” which the Bible mentions as the color of ceremonial robes donned by high priests and ritual prayer tassels worn by the common Israelite.
Though scientists and scholars are still debating the exact shade of the ritual blue, the dye used is modeled after a 2,000-year-old textile, above, and is produced from sea snails found in Israeli waters.
What was known about tekhelet (pronounced t-CHELL-et) was that the Talmud said it was produced from the secretion of the sea snail, which is still found on Israeli beaches.
Traditional interpretations have characterized tekhelet as a pure blue, symbolic of the heavens so that Jews would remember God. Not so, according to an Israeli scholar who has a new analysis: tekhelet appears to have been closer to a bluish purple.
The scholar, Zvi C. Koren, a professor specializing in the analytical chemistry of ancient colorants, says he has identified the first known physical sample of tekhelet in a tiny, 2,000-year-old patch of dyed fabric recovered from Masada, King Herod’s Judean Desert fortress, later the site of a mass suicide by Jewish zealots after a long standoff against the Romans.
UPDATE (2 February): A recent article in The Forward on the latter: Dyeing To Be Holy: Snails Make Tzitzit Blue Again. (HT Joseph Lauer and Gerald Rosenberg.)