Gemstone :
Opal

Birthstone Month :
Opal is the birthstone for the month of October.

Zodiac :
Opal is associated with the zodiac signs of Libra and Scorpio.

Chemical Symbol :
SiO2n.H2O

Chemical Make-up :
Opal is a Hydrated Silicon Dioxide that lacks a distinct crystalline structure and contains between 2 and 21 percent of water within its mineral structure.

History & Lore :
Opal is derived from the Latin word 'Upala' and the Greek word 'opallios', both meaning “precious stone”. The name Cat's eye is derived from the phenomena displayed by this stone known as chatoyancy, which in French literally means “cat's eye”.

The Roman scholar and famous author Pliny once described Opal as a gemstone that combines the best possible characteristics of the most beautiful of gemstones: the fine sparkles of Almandine, the shining purple of Amethyst, the golden yellow of Topaz, and the deep blue of Sapphire, “so that all all colors shine and sparkle together in a beautiful combination.”

In Greek mythology, Opal was believed to be formed from the joyous tears wept by Zeus after he defeated the Titans. It was also believed by the Greeks that the owner of Opal would obtain the power of giving foresight and the light of prophecy.

In ancient Arabic times it was believed that opals fell from the heavens in lightning, the flashes giving the stone its fire and flare.

It is said that Opal was part of Cleopatra's famous jewelry collection, and that she used the stone to attract the attention of Mark Anthony.

Opal is said to be a symbol of faithfulness and is believed to assist the wearer with finding true love. Opal is also believed to cure depressions and bring confidence to the wearer. Opal helps to open unused parts of the mind in order to increase creativity and mental capacities.

Availability :
Opals were relatively rare leading up to the mid 19th century until there was a rich discovery in Australia that has supplied an adequate amount of Opal that currently satisfies demand.

Sources :
Australia is the World's most important source of Fine Opals, and is estimated to account for almost 95% of all mined Opals. There are also known Opal deposits in Brazil, the Czech Republic, England, Honduras, Mexico, South Africa, and the United States.

Evaluation :
Opal is rated at 5.5 to 6.5 on Moh's Scale of Hardness. As Opal is relatively soft and fragile it is often made into doublets or triplets - backed with plain black Opal and fronted with clear quartz. These are ideal for rings or any piece that is likely to be receiving rough treatment. The physical structure of Opal is unique. Tiny spheres of silicon dioxide form a pyramid shaped grid interspersed with water. Tiny natural faults in this grid cause the characteristic "play of color". The effect is similar to the rainbow colors displayed on a soap bubble, only much more dramatic.
Opals vary widely in body color, with white the most common. Black is considered the most valuable as it enhances and accentuates the play of color. Fire Opal (yellow, orange or red), is often faceted and can resemble Ruby. Green and Blue Opals are very rare.

Combining body color and play of color we are faced with infinite possibilities, so pricing is complex. Size is also a factor with the carat price for larger stones accelerating accordingly. The intensity of the play of color and the extent to which it covers the Opal's surface also count.

Common Cuts :
Fine Opal stones are cut and polished to round or oval cabochons or other softly domed shapes so as to display the best color. Only the very finest qualities of Fire Opal are suitable for faceting.

Routine Enhancements :
Opals are occasionally enhanced with colorless oils, wax or resins which reduce the visibility of the inclusions and improves the overall clarity of the stone. Some Opals are smoke-enhanced to create Black Opal.

Care & Cleaning :
Opals are relatively soft gemstones and should be worn with special care because they are prone to scratching and chipping. Always avoid sudden temperature changes with Opals as this can can cause the stone to crack or craze.
Because opals are composed of a small percentage of water, always be careful not to allow them to freeze or dry out. It is recommended that you have Opals cleaned by a professional jeweler. However, if home cleaning is undertaken it should be done with room temperature water and a mild detergent. A soft brush or cloth can be used safely. Always store your opal jewelry in a fabric-lined box alone or away from other harder jewelry items so as to avoid damage.