Fire Opal

Fire Opal is an unusual variety of opal from Mexico. You will find two main types of fire opal. One is a translucent yellow, orange or red with no play of color. The other is brownish and has a play of color somewhat similar to the better known precious opal. Fire opals, like all opals, are delicate gemstones, sensitive to stress. Thus they are best suited for earrings, brooches, and pendants and need to be treated carefully. Opal is the birthstone for those born in October.

The colors range from yellow to orange to brown and red. The best stones usually show a vivid burnt red-orange combination. Opals are delicate gemstones. Their most significant weakness has to do with their water content. If an opal is allowed to dry, it will crack and fade. If you live in a very dry climate, or keep them in a dehumidified room, some precautions are necessary. Keeping them in a tight plastic bag, with a damp piece of cotton or fabric will prevent dehydration. Because of their water content, opals are also sensitive to sudden changes in temperature.

Being somewhat soft, they scratch easily. Realize that a large component of ordinary dust is quartz at 7 on the Mohs scale of hardness. At 5.5 to 6 in hardness, simply wiping the dust off an opal will gradually reduce its polish. The solution is to clean your opals using a soft cloth. The rarest and thus the most highly esteemed, is the intense orange-red color of the fire opal from Mexico. Fire opal looks best viewed in daylight (just after sunrise and before sunset), which exposes its exceptional fire and color play most favorable. Unlike many opals, good-quality fire opal can be translucent to transparent. Lesser grades tend to take a cloudy appearance. Fire opals are often facetted, but can also be seen in cabochon. The brown fire opals exhibiting a play or color are always cut as cabochons. The finest fire opals are found in Mexico. Other deposits are in Brazil, Guatemala, the United States and Australia. Fire opals are usually untreated.

Fire Opal Gemology
Species: Opal
Color: Yellow to orange, orange red
Chemical composition: SiO2 .nH2O hydrous silicon dioxide
Crystal system: Amorphous; kidney- or grape-shaped aggregates
Hardness: 5.5-6.5 (Mohs scale)
Specific gravity: 1.98 - 2.50
Refractive index: 1.37 - 1.52
Birefringence: None
Color of streak: White
Absorption spectrum: 700 - 640, 590 - 400
Fluorescence: greenish to brown

The name opal comes from the Greek "Opallus" which means to see a change in color. Later, the Latin word "opalus" evolved, meaning precious stone. For ages people have believed in the healing power of opal. It is reported to be able to solve depressions and to help its wearer find the true and real love.

Opal is the birthstone for those who are born in October.