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  : : Fire Opal Information
Information sur la pierre précieuse l'opale de feuInformación del ópalo de fuego

Fire Opal Gemstone Information

About Fire Opal - History and Introduction

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.

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Fire Opal
Identifying Fire Opal Back to Top

Fire opal is one of the many different varieties of opal available. Fire opal looks best when viewed in daylight just after sunrise or before sunset, which exposes and maximizes its exceptional color. Its distinctive colors are what separates fire opal from other opal varieties. Fire opal does not exhibit much play of color like other varieties of opal. Fire opal typically exhibits a hazy or cloudy appearance, which is a result of slight opalescence (adularescence). Opalescence is often used to refer to 'play of color', but the term should only be used to describe the milky iridescence of common opals, which do not possess any play of color.

Fire Opal Origin and Gemstone Sources Back to Top

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. Mexican fire opal is sometimes cut in its host material; this type of opal is sometimes referred to as 'Cantera opal'. 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.

Buying Fire Opal and Determining Fire Opal Value Back to Top

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.

Fire Opal Treatment

Fire opal is not known to be treated or artificially enhanced in any way.

Fire Opal Gemological Properties: Back to Top
Chemical Formula: SiO2_nH2O Hydrous silicon dioxide
Crystal Structure: Amorphous; kidney or grape-shaped aggregates
Color: Yellow to orange, orange-red
Hardness: 5.5 to 6.5 on the Mohs scale
Refractive Index: 1.37 to 1.52
Density: 1.98 to 2.50
Cleavage: Indistinct
Transparency: Transparent to opaque
Double Refraction or Birefringence: None
Luster: Subvitreous to waxy, resinous
Fluorescence: Usually none

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

Fire Opal: Related or Similar Gemstones: Back to Top
Boulder Opal
Boulder Opal

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.

Most Popular Related Gemstones:

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

Lesser-Known Related Gemstones:

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.

Fire Opal Mythology, Metaphysical and Crystal Healing Properties Back to Top

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.

For ages people have believed in the healing power of opal. It is reported to be able to solve depression and to help its wearer find true and real love. Opal is also said to stimulate originality and creativity. Opal is porous and because of this, it is quite absorbent. Due to its ability to absorb, it is thought that it can pick up the thoughts and feelings of people and amplify emotions. Fire opal carries strong karmic powers, representing justice and also providing protection for its wearer.

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.

Disclaimer: Metaphysical and Alternative Crystal Healing Properties are not to be taken as confirmed advice. Traditional, Ceremonial and Mythological Gemstone Lore is collected from various resources and does not represent the sole opinion of SETT Co., Ltd. This information is not to replace the advice of your doctor. Should you have any medical conditions, please see a licensed medical practitioner. GemSelect does not guarantee any claims or statements of healing or astrological birthstone powers and cannot be held liable under any circumstances.
Fire Opal Gemstone and Jewelry Design Ideas Back to Top

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 Opal Gemstone and Jewelry Care and Cleaning Back to Top

How to clean your gemstonesFire 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.

  • First Published: September-11-2006
  • Last Updated: May-30-2014
  • © 2005-2014 GemSelect.com all rights reserved.
    Reproduction (text or graphics) without the express written consent of GemSelect.com (SETT Company Ltd.) is strictly prohibited.
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