Opal
Thirty million years ago, seasonal rains poured onto the earth’s crust, soaked the dry ground, and carried dissolved silica downward. The dry season then followed- evaporating the water and leaving behind the silica. This silica, trapped between the cracks and layers of sedimentary rock, formed what we now know as opal. The gem acquired its dazzling, prismatic characteristics, also known as “play of color”, from the billions of submicroscopic silica spheres that have arranged themselves in a uniform grid. The gaps between this grid diffract white light into the rainbow of colors that we see.
Opal comes in many types: black opal, white opal, crystal opal, water opal, boulder opal and fire opal. Black opal, which has subcategories like black crystal opal, grey base, semi black, are the most expensive. White opal, on the other hand, dominates the commercial market. The hardiest and most durable is the boulder opal. Most opal, roughly 90%, comes from Australia. One specific variety, fire opal, is almost exclusively found in Mexico. Other minor producers of opal are Ethiopia, the US, Canada, and Honduras.
Opal comes in many types: black opal, white opal, crystal opal, water opal, boulder opal and fire opal. Black opal, which has subcategories like black crystal opal, grey base, semi black, are the most expensive. White opal, on the other hand, dominates the commercial market. The hardiest and most durable is the boulder opal. Most opal, roughly 90%, comes from Australia. One specific variety, fire opal, is almost exclusively found in Mexico. Other minor producers of opal are Ethiopia, the US, Canada, and Honduras.
