Gemstone the stone such as color zoning (the uneven distribution of coloring within a gem) and asteria (star effects). The Greeks, for example, greatly valued asteria gemstones, which were regarded as powerful love charms, and Helen of Troy was known to have worn star-corundum. Aside from the diamond, the ruby, sapphire, emerald, pearl (not, strictly speaking, a gemstone), and opal have also been considered to be precious. Up to the discoveries of bulk amethyst in Brazil in the 19th century, amethyst was considered a "precious stone" as well, going back to ancient Greece. Even in the last century certain stones such
George Stone (bishop) tact, and qualities as a popular leader. Horace Walpole, who gives an unfavourable picture of his private character, acknowledges that Stone possessed "abilities seldom to be matched", and give him credit for charity and generosity; and he had the distinction of being mentioned by David Hume as one of the only two men of mark who had perceived merit in that author's "History of England" on its first appearance. He was himself the author of several volumes of sermons which were published during his lifetime. George Stone (bishop) George Stone (1708 – 19 December 1764) was the Church of Ireland