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
Diamond (gemstone) to help authenticate Canadian diamonds. This is a very stringent tracking system of diamonds and helps protect the 'conflict free' label of Canadian diamonds. Currently, gem production totals nearly of cut and polished stones annually, and over of mined diamonds are sold for industrial use each year, as are about of synthesized diamond. Diamond (gemstone) A diamond (from the "adámas", meaning "unbreakable", "proper", or "unalterable") is one of the best-known and most sought-after gemstones. Diamonds have been used as decorative items since ancient times; some of the earliest references can be traced to 25,000 - 30,000 B.C. The hardness of