Fire Opal Gemstone Information

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Fire opal is a gem-quality form of amorphous hydrated silicon dioxide with no crystalline structure. Like other opal gemstones, between three and ten percent (and in some cases as much as 21 percent) of the weight of fire opal is water. Owing to its high water content, fire opal is rather delicate and should be protected from heat and prolonged exposure to strong light, to avoid drying and cracking. Fire opal is not known for its play of color, but rather for its vivid body color. In fact, most fire opal does not exhibit any play of color, although it may occasionally exhibit flashes of bright green.

The name 'fire opal' is derived from its 'fiery' orange color, though it can also be white or brown. Darker brownish fire opal will typically exhibit more play of color than fiery golden colored varieties. Fire opal that exhibits no play of color is sometimes referred to as jelly opal. Unlike most opal, fire opal occurs with good transparency and because of this, it is usually faceted rather than cut en cabochon. On the other hand, brownish fire opal is usually cut en cabochon to enhance and maximize its desirable play of color effect.

Identifying Fire Opal Fire Opal Origin and Sources Buying Fire Opal Fire Opal Gemological Properties Fire Opal - Related Gemstone Varieties Fire Opal Metaphysics Fire Opal Jewelry Fire Opal Gemstone Care
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Fire opal is associated particularly with Mexico and is mined in the Mexican states of Queretaro, Hidalgo, Guerrero, Michoacan, Julisio, Chihuahua and San Luis Potosi. The most important mines in Queretaro were discovered in 1835 and are still producing today. Some opal from Mexico exhibits a bluish or golden internal sheen; this is known as Mexican water opal or hydrophanous opal, rather than as Mexican fire opal.

Small quantities of fire opal can also be found in Oregon, USA, Guatemala, Australia and British Columbia, Canada. Significant deposits of fire opal have also more recently been found in Northeast Brazil.

Fire Opal Color

The color range of fire opal can be quite wide, and some pieces display several colors in a single stone. The colors range from yellow to orange and from brown to red. The best stones usually show a vivid burnt red-orange combination. The brilliant sunny yellows are highly regarded, but the more saturated orange and orange-red stones are especially valuable. Brazil produces a golden variety of fire opal that resembles hessonite garnet or hyacinth zircon.

Fire Opal Clarity and Luster

Unlike most opal, good quality fire opal can be translucent to transparent. Lesser grades tend to have a cloudy appearance. Fire opal has a subvitreous, waxy to resinous luster when cut and polished.

Fire Opal Cut and Shape

Most opal stones are typically opaque and cut en cabochon, but fire opal can be transparent to translucent. Thus, you will often find higher-grade transparent material facetted. Brown fire opals which exhibit play of color are typically cut as cabochons. The most popular fire opal shapes include traditional ovals, rounds, cushions and pears. Cantera opal is a trade name used for fire opal that has been cut with its host rock intact.

Fire Opal Treatment

Fire opal is not known to be treated or artificially enhanced in any way, though imitation opals do exist.

Please refer to our Gemstone Glossary for details of gemology-related terms.

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There are many varieties of opal available that can be classified as either precious opal or common opal. Ammonite, labradorite, mother-of-pearl and moonstone can sometimes be mistaken for opal. Mexican fire opal is sometimes cut in its host material; this type of opal is sometimes referred to as 'Cantera opal'.

Most Popular Similar or Related Gemstone Varieties and Trade Names:

Chocolate opal, boulder opal, black opal, common opal, white opal, matrix opal, opal in matrix and doublet opal are the most popular opal types.

Lesser-Known Similar or Related Gemstone Varieties and Trade Names:

Cantera opal, Layer opal, agate opal, angel skin opal, wood opal, honey opal, hyalite, hydrophanous opal, porcelain opal, moss opal, jelly opal, crystal opal, harlequin opal, opal triplets, girasol, prase opal, pipe opal and wax opal are among the rarer opal varieties available today.

According to an old Australian Aboriginal legend, the Creator came down from the heavens on a rainbow and delivered a message of peace for all mankind. Stones that were near the place where His feet touched the ground suddenly came to life and began to sparkle. This was believed to be the birth of opal. 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.

Traditional opal, with its unique play of color, has been valued since Ancient Rome. During the Middle Ages, precious opal was regarded as especially lucky because it displayed the colors of many different gemstones. However, not every culture has shared this view. A well-known Russian superstition associates precious opal with the evil eye. Opal is also the official birthstone for October and those who wear opal can benefit from its many astrological powers.

There are several advantages to buying loose gemstones, rather than preset jewelry. Once a stone has been mounted, it is almost impossible to know its actual quality because the setting often hides or obscures blemishes. Buying loose stones can also provide you with more variety and value as opposed to buying prefabricated stock jewelry designs.

Lapidaries cure fire opal by drying it before cutting, to reduce instability and make it less delicate. But due to its relative softness (5.5 to 6.5 on the Mohs scale), it is best suited for pendants, earrings and brooches. Despite being a softer, fragile stone, fire opal is often used in gemstone rings even though it is not recommended. When wearing fire opal as a ring, it is best to choose a protective style setting such as a bezel design.

Note: Buy colored gemstones by size and not by carat weight. Colored stones vary in size-to-weight ratio. Some stones are larger and others are smaller than diamond by weight in comparison.

Fire opals are delicate gemstones and do require a bit of opal care. Opals in general have a high level of water content. In fact, the water content can constitute up to 21% of its weight. This is the reason why opals are vulnerable to 'crazing' caused by dehydration. If an opal is allowed to dry, it will crack and fade. The drying will cause cracks and fissures that reach the surface. It is very important to always properly store and maintain your opal stone to protect it from drying out. Opals are very sensitive to sudden temperature fluctuations. When storing opal, it is highly reccommended to place a moist cloth or cotton ball inside a sealed plastic bag along with the opal to prevent dehydration.

Opals are fairly soft and because their hardness ranges from 5.5 - 6.5 on the Mohs scale, they can be easily scratched. A sizeable component of ordinary dust is quartz, which measures up to 7 on the Mohs scale of hardness. Since opals are 5.5 to 6.5 in hardness, simply wiping the dust off an opal will gradually reduce its desirable polish. Fire opal stones can be cleaned or rinsed under warm water with a soft clean cloth. Never use bleach, chemicals or any ultrasonic cleaners to clean your opal stone. The vibrations alone can cause an opal stone to crack. Always remove opal jewelry before engaging in household chores or any vigorous sports or activities.

Damaged opals are extremely difficult to repair. Current repair methods are not official in the gem world, and so any method used today is merely experimental. Typically, it is better to replace a damaged opal stone, rather than repair it. The most common methods used to repair damaged opals include impregnating the stone with resin to fill in fractures or cracks.