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
Gemstone characteristic that lends value to a gemstone. Apart from jewelry, from earliest antiquity engraved gems and hardstone carvings, such as cups, were major luxury art forms. A gem maker is called a lapidary or gemcutter; a diamond cutter is called a diamantaire. The traditional classification in the West, which goes back to the ancient Greeks, begins with a distinction between "precious" and "semi-precious"; similar distinctions are made in other cultures. In modern use the precious stones are diamond, ruby, sapphire and emerald, with all other gemstones being semi-precious. This distinction reflects the rarity of the respective stones in ancient times,