Thousands of years ago, one shade of blue was prized above all others for those of the Jewish faith. Tekhelet protected the Ark of the Covenant, the headdresses donned by Jewish high priests and the robes worn by ancient kings and princes—that is until 70 A.D., when Rome’s imperial forces razed Jerusalem’s Second Temple and crushed the subsequent uprising of Jews, bringing an abrupt end to the color's dominance over the Near East. As the Jewish community languished under imperial control, dye workers started to forget the secrets to making tekhelet, from details as rudimentary as the color’s exact hue to the method of its production.
Now, Noga Tarnopolsky reports for the Los Angeles Times, an exhibition at Jerusalem’s Bible Lands Museum revisits the legacy of tekhelet in an exhibition that traces the color blue’s significance across the ancient world. The show, entitled Out of the Blue, features not only a historical overview of tekhelet and its royal purple counterpart, argaman, but an exploration of the multifaceted shades beyond Biblical blue, from 2,000-year-old textiles to a Mesopotamian horned crown adorned with lapis lazuli.
Older artifacts featured in the show highlight the significance of blue across the Near East: As Marissa Newman explains for the Times of Israel, the exhibition explores ancient Egyptians’ experimentation with the blue lapis lazuli stone, which sparked the production of the first imitation dyes, and the color’s recurring presence in different cultures’ ritual items and jewelry.
Punctured snail shells dating to the 10th through 7th centuries B.C. showcase how the ancients extracted the substance needed to create the unique shade.
Tekhelet’s true hue has fascinated rabbinic scholars for centuries. The New York Times’ Dina Kraft reports that in modern Hebrew, the word translates to light blue—a verdict seconded by medieval philosopher Maimonides, who likened it to the color of “the clear noonday sky”—but according to Rashi, another prominent medieval scholar, tekhelet is closer to the color of a darkening evening sky. A passage in the Talmud provides an additional clue, Tarnopolsky notes, stating that “the blood of the snail and chemicals” must be boiled together to create the Biblical blue.
A major break in the ongoing debate arrived in 1985, when chemist Otto Elsner seemingly chanced upon the formula for tekhelet. As Newman explains, previous researchers had hoped to identify the Murex trunculus snail as the key to the color’s creation, but the dye produced by the snail appeared closer to purple than blue. When Elsner exposed a sample of snail dye to ultraviolet light, however, the color transformed from purple to that of a pale blue sky.
The similarities between historical accounts of tekhelet and Elsner’s rich blue dye were enough to convince physicist and snail dye expert Baruch Sterman that the mythical hue had finally been found. In 1991, Sterman co-founded Ptil Tekhelet, an Israeli-based non-profit dedicated to the revival of tekhelet. He also authored The Rarest Blue: The Remarkable Story of an Ancient Color Lost to History and Rediscovered, which was published in 2012.
In a reflection of tekhelet’s lasting importance to the Jewish people, the show features a flag flown outside of the United Nations upon Israel’s acceptance in May 1949. The blue-and-white striped pattern mirrors the design of the tallit, or prayer shawl, and reinforces the centuries-old association between Jewish identity and tekhelet.
Newman notes that thousands, or even tens of thousands, of snails were required to create just one kilogram of the dye, so perhaps it won't surprise you to learn that Sterman estimates tekhelet fabrics were once “worth up to 20 times their weight in gold.”
Today, it’s far simpler—and cheaper—to acquire your own example of tekhelet, but as curator Yaara Keydar tells the Los Angeles Times’ Tarnopolsky, that hasn't stopped the “cult of blue” from retaining its powerful hold on public imagination.