Gem Library

BUYER’S OVERVIEW:
Fire Opal is considered to be a semi-precious gemstone and while somewhat limited in nature, clear, large, natural stones are available. The fiery, warm glow of the Fire Opal beguiles gemstone enthusiasts the world over and while the radiant orange color simply cannot be overlooked, not all fire opals are the same. A deep rich red orange is the most valuable color and some stones have a strong play of color, these are the most rare. Opals love (and need) to be worn a lot as this enables the stone to maintain its water balance. Opals absorb moisture from the wearer’s skin and from the air.

COLOR:
Fire Opal come in a wide range of colors; yellow, red, orange, brown, or colorless; with or without play of color.

APPEARANCE:
Transparent to semitransparent

Phenomena:
Fire Opal exhibits play-of-color in some gems.

SIZE RANGE:
From melee (0.01) to 100 carats; large specimens are available.

TYPICAL CUTTING STYLES:
Transparent: faceted and beads
Semi transparent to Translucent: cabochons, beads and carvings.

POSSIBLE ENHANCEMENTS & TREATMENTS:
Fire opal has no known enhancements.

HARDNESS:
5 to 6½ on the Mohs scale.

BEST USE OF THE GEMSTONE:
Fire Opal is not a strong gemstone and as such, earrings, pendants, pins, and tie tacks are probably the safest choice for this stone. Rings should be limited to occasional wear and the stones should be set with a protective setting. Avoid rough handing.

CARE & CLEANING:
It is best to never expose colored gemstones to cleaning solvents or chemicals of any kind. Opals love to be worn a lot as this enables the stone to maintain its water balance. Opals absorb moisture from the wearer’s skin and from the air.
Common cleaning methods include:
Ultrasonic: never
Steamer: never (very heat sensitive)
Warm soapy water: safe
Reaction to Chemicals: can be damaged by acids.
Reaction to Heat: very heat sensitive, heat will destroy play-of-color and cause gem to crack
Stability to Light: like all opals, it should not be exposed to intense light over long periods.

INTERESTING FACTS ABOUT THIS GEMSTONE:
The name Opal comes from the Greek word, “Opallos”, meaning “to see a change of color”. Opal is a form of non-crystalline silica gel that was formed millions of years ago as water seeped over silica bearing rock and pooled in crevices and cracks in the sedimentary rock. In 1963 it was discovered that Opal is composed of minute spheres of silica in closely packed arrangements. Spheres in a regular pattern produce the best display of play-of-color as light passes through the transparent spheres and is scattered by the voids between the spheres. Small spheres produce violet, indigo, blue and green, the large spheres produce red and orange with red being the rarest color.

Fire Opal had been known in Mexico since ancient times but was forgotten until the mid 1800’s when the fiery treasures that lay hidden in the Mexican highlands were once again brought to light and mining resumed. Today, Fire Opal is so highly regarded that it has been named the national gemstone of Mexico. For the most part Opal is found in the rock strata near many extinct volcanoes, typically in cavities and crevices dotting the canyon walls. Fire Opals have also been found in an agate mine near Campos Borges in the South Brazilian State of Rio Grande do Sul. While the gems found in this location were yellow to orange often with slight clouding and no play of color, they were remarkable for the sheer size of the raw stones, some as large as a man’s fist.

DESIGNATION:
Opal is the birthstone for October and the gemstone for the 14^th wedding anniversary.

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