For almost a hundred years, from 1688 to 1786, Anglo-Dutch Jews moved to Madras and played a major role in the trade of precious stones. Strange as it may seem, the 'natives' were fascinated by coral and were willing to trade even diamonds for it. The Jewish traders typically had an arrangement where one brother was a free merchant near Fort St George, another was based in London and a third in Amsterdam. That helped: coral from the Mediterranean, which was much sought after by the people of India, was shipped to Fort St George through London. (In return, the merchants of Leghorn, Naples and other cities on the Mediterranean seem to have been paid in pepper). Diamonds obtained as payment for this coral were sent to Amsterdam for cutting and polishing.
It appears that the Jews played a significant role in moving the centre of the coral trade from Goa (then with the Portugese) to Madras, which would explain their pre-eminence in this trade in the early days of the city. However, with the discovery of diamonds in other parts of the world, their value fell and the trade became less lucrative. Also, there appears to have been a shake-up in 1765 with the bust of a diamond smuggling ring, in which 3 Jewish agents from Madras (and the governor of Madras) were alleged to have been involved.
The trade was then taken over by the Nagarathars. Whether they continued to trade coral or not, they took up offices in the street vacated by the Jewish traders. By this time, the street was itself so closely associated with the coral trade that it was called Pavazhakkarar Theru - Coral Merchants' Street. It is likely that anyone commencing trading activities there would be dubbed a Pavazhakkarar, whether coral was part of his bill of materials or not. And in keeping with the fascination for red coral, this gift from 'Coral Naiker Madras' to the city's Corporation, has been topped off with bright red paint!
The book "Diamonds and Coral: Anglo-Dutch Jews and Eighteenth-Century Trade", by Gedalia Yogev seems to have some fascinating accounts of the Jews of Madras, going by excerpts found here!