Fascination with the hypnotic lavender hues of February’s birthstone, the amethyst, dates back to ancient Greece, when the gem was worn to ward off drunkenness and ill will, and to support clear thinking. (Its name, derived from the Greek word amethustos, means “not drunken.”) Throughout the centuries, amethysts have been mined from Brazil, Uruguay, Zambia, and the southwestern United States to ornament everything from fashion-forward jewelry to crown jewels. Have a look at these f…