Revered as a symbol of hope, fidelity, and purity, opal was dubbed the Queen of
Gems by the ancient Romans because it encompassed the colors of all other gems.
Opal is prized for its unique play of color, the ability to diffract light into flashes of
Opal occurs in different colors, ranging from semi-transparent to opaque. The most
common is white opal. Crystal or water opal has a colorless body. The most valued
variety, black opal, has a dark blue, gray, or black body color. Boulder opal combines
precious opal with the ironstone in which it forms. Bright yellow, orange, or red fire
opal are quite different from the other varieties of opal. Their day-glo tones, which
are translucent to transparent, are beautiful with or without play of color. Opal, along
with tourmaline, is the birthstone for October and the suggested gift for the fourteenth
Today’s supplies of opal come primarily from Australia, Mexico and the United States. Most opals are not faceted but cut
into rounded or free-form cabochons that enhance their play of color.
Although opal is rarely enhanced by methods other than cutting and polishing, opals can be treated to bring out their play of
color. One technique is to immerse white, gray, or black opal in a sugar solution and then in strong sulfuric acid, which
carbonizes with the sugar and leaves microscopic carbon specks that blacken the body color, making its flashes of color
more visible. Opals can also be permeated with colorless oil, wax, resin, plastic, and hardeners to improve their appearance
and durability. Occasionally, some thinner or translucent opal may be painted with a black epoxy on the backside of the
gemstone to darken the body color and improve the play of color. Fire opal is not commonly enhanced.
Opal, with or without enhancement, should be treated with some care. Opal is softer than many other gemstones and
should be stored carefully to avoid being scratched by other jewelry. It should also be protected from blows, as exposed
corners can chip. Opal should not be exposed to heat or acid. I can tell you how to best care for your opal.