In recent years it has become common place to see Jews wearing Tzitzit in blue and white.  The blue string, known in Hebrew as Tekhelet, was worn on Tzitzit strings on the past, but disappeared from use for several millennia.  However, numerous attempts were made to re-identify the animal that supplies the Tekhelet dye throughout history.  What follows is a short history of Tekhelet.

Tekhelet is identified in Jewish sources as being a blue color, somewhere in between greenish-blue and blue that borders on purple.   The exact shade seems to be closest to a color reflecting that of the sky.  Tekhelet is identified as coming from an animal called the Hilazon, which most recently has been identified through scientific and archeological research as a small snail known as the Murex Trunculus.

According to Archaeological research, Tekhelet originated in Crete and then spread from there across the Middle East, particularly in Egypt, Israel and Lebanon.  Tekhelet was in use roughly until 500CE, although there were periods in which Roman Emperors, specifically Caesar, Augustus, Nero and Constantius, declared the wearing of Tekhelet to be illegal for anyone outside of the ruling classes.  With the Arab conquest of Israel in 639, Tekhelet production ceased completely and Jews began wearing Tzitzit without Tekhelet for the next two millennia.

In the year 1500, research began to re-identify the animal Tekhelet came from in the Christian world.  However, it wasn’t until the late 1800s when the Jewish community paid attention to the research and attempted to identify the Hilazon.  The only discussion was on theoretical grounds and was mostly based on the rulings of Maimonides regarding Tekhelet.  In the late 1880s, the Admor (Rabbi) of Radzyn – Rabbi Gerson Leiner – identified the Hilazon as the common cuttlefish or a squid.  However, this was debunked via science over the next 100 years and the Murex Trunculus snail was identified as most likely being the Hilazon.

In 1913, Rabbi Isaac Herzog declared the Hilazon to be the Murex Trunculus and nearly 70 yeras later, Dr. Otto Eisner backed Rabbi Herzog by using the blood of the snail to produce Tekhelet colored strings.  In the 1980s and 1990, a rabbi named Eliyah Tavger successfully used the process stipulated by the Radzyner Rebbi and Maimonides to recreate Tekhelet for Tzitzit.

In the modern era, Tekhelet is developed exclusively in Israel and has resurged in use in Jewish communities of all religious levels.  In addition, Professor Zvi Koren of Hebrew University has conducted years of research that prove Tekhelet comes from the Murex Trunculus snail.  However, it should be noted that there are still some Jewish communities that reject the validity of any type of Tekhelet because of the belief that once a tradition is lost, it cannot be reinstated until the Messiah arrives.