For ancient Israelites, tekhelet was God’s chosen color. It was the color of the sumptuous drapes adorning Solomon’s Temple (2 Chronicles 3:14) as well as the robes worn by Israel’s high priests (Exodus 28:31). Even ordinary Israelites were commanded to tie one string of tekhelet to the corner fringes (Hebrew, tzitzit) of their garments as a constant reminder of their special relationship with God (Numbers 15:38–39).
But how do we know what color the Biblical writers had in mind? While tekhelet-colored fabrics and clothes were widely worn and traded throughout the ancient Mediterranean world, by the Roman period, donning tekhelet and similar colors was the exclusive privilege of the emperor. And so it happened that sometime around the seventh century C.E., probably hastened by the Islamic conquest of the Levant, the source and identity of tekhelet, and knowledge of its manufacture, slipped into obscurity.