Opal Jewelry - What is a Boulder Opal?
Opal jewelry is some of the most sought after gemstone jewelry in the world, being fifth after diamonds, sapphires, rubies and emeralds. This is because opals are some of the most beautiful gemstones available. And whilst most people have probably heard of black, white and fire opals, boulder opals are probably less well known. So why are they becoming so popular? The body colors of these gemstones are derived from the host rock in which they formed and are categorised as black, gray, white, fire, crystal or jelly. Despite this, opals actually exhibit a wide variety of colors, including pink, fiery orange, tropical blue and others. However, they are most prized for their internal play of color and fiery opalescence. In a good gemstone, the effect is like the rainbow display on the surface of a soap bubble. Opals have a unique physical structure. They are comprised of silicon dioxide, which is also the major component of sand. However, in opal, the silicon dioxide forms minute sphe...