Hello jO jO,
This the story in short. For more information go to tekhelet.com .
Attempts have been made in the past to find the lost method of extracting the tcheles dye, the main obstacle having been the difficulty in identifying the sea creature (chilazon)that provides the dye. The Rizhnitzer rebbe in the 1800s thought he had found it, but it had three problems. One, it did not match any of the criteria that the gemara mentions as simanim for the creature. Two, many other creatures can produce the same exact dye. Three, the dye itself did not fulfill the criteria of the gemara and so it was clear that there was nothing unique about the rizhnitzer dye other than that it was a pretty color of blue. Tcheiles it was not.
Rav Yakov Herzog zt”l, Chief Rabbi of Israel after Rav Kook, a true Torah genius, had written his doctorate as a young man on this subject, and was convinced he had found the true chilazon . The process of the extraction of the dye produced ALL of the necessary properties of true tcheiles as stated in the gemara, except for one. The problem? Tcheiles is supposed to be blueish, and no matter how hard he tried, the color that he found was….purple. Rav Herzog eventually became discouraged and gave up on his attempts. He died still wondering where he had gone wrong.
By chance, a relatively short time ago, someone was playing with the process of Rav Herzog, and sure enough, came up with the same purple color. However, without serious thought he left the bottle with the purplish wool on the windowsill, and when he came back the next day, lo and behold, the color was sky blue (domeh larakia). He had accidentally discovered the missing link. At a specific stage in the process, the dye had to be exposed to sunlight, which within minutes turned it from purple to blue. Rav Herzog did all his experiments inside a laboratory and so the wool was never exposed to sunlight at the right moment and hence remained a fast purple.
I must mention that this tcheiles fulfills every single nuance that the gemara describes, including the indistinguishability from kala Ilan, a plant source dye which the gemara says looks identical. Chemical analysis shows that the two are indeed chemically identical.
The tcheiles institute conducts tcheiles making workshops in the western galil, I participated in one, it was fun and it works. Obviously for tztitzis purposes the the process must be strictly controlled, we are not dealing with finger painting after all. This is a mitzvah mede’oraiso.
One more point. Whether bizman hazeh one should wear tcheiles is a separate issue and has many sides to it. Many rabbonim claim that since the mesorah was lost, we cannot reinstitute it. This is not a simple issue and is beyond the scope of a site such as this. But it is beautifully clear that the original tcheiles has indeed been identified.