Opal

Iridescence is the word that you spontaneously associate with opals. Classically found in Australia, even today 95% of all opals are mined in Australia. The remaining five per cent are mined in Mexico, and in Brazil’s north, also in the US states of Idaho and Nevada, but recently the stones have also been found in Ethiopia and in the West African country of Mali.

There is a large group of opals, with a number of gemstones, all of which show a changing play of colors which experts call ‘opalising’. Depending on the main color, they are classed as Dark or black opal, white or light opal, boulder opal and the famous Mexican ‘fire opal’. If opals lack the characteristic play of colors, they are called’ common opal’.

Composition and features :

Opals are not very hard: they only achieve 5.5 to 6 on the Mohs’ scale. Therefore they need a protective setting. In earlier days Opal’s sensitive surface was often oiled, but today also sealing them with colorless artificial resin has become quite popular.

Due to the differing percentage of water, Opals easily tend to become brittle. They always contain water – usually between 2 and 6 per cent, but sometimes even more. Thus if stored too dry or exposed to heat over a longer period of time, Opals will show fissures and the play of color becomes paler. Therefore, Opal jewelry should be worn as often as possible, for then the gemstone receives the needed humidity from the air and from the skin of its wearer.

Opal’s color play emanates a very special fascination. In 1960s, when Opals were studied with electron microscopes, it was discovered that small spheres from silica gel caused refractions manifestations, which are responsible for the fantastic play of colors.

Opal is the October birthstone and the 14th anniversary gift. Opals are supposed to further enhance the positive characteristics for people born under the zodiac sign of Cancer. Black Opal is recommended to those born under Scorpio, and Boulder Opal is the lucky stone for Aries.

People believe in the healing power of Opal. It is reported to be able to lift depression and to help its wearer find real love.

History and Legends :

The name Opal was probably derived from Sanskrit “upala”, meaning “valuable stone”. This was probably the root for the Greek term “opallios”, which translates as “color change”.

Of all the legends that surround opal, the most well known is that of ancient dream time of the Australian aborigines. It is reported in their legends that the creator came down to Earth on a rainbow, in order to bring the message of peace to all the humans. And at the very spot, where his foot touched the ground, the stones became alive and started sparkling in all the colors of the rainbow. That was the birth of the Opals.

Opals lived on in distinct insignificance up to the first half of the 19th century. Then they emerged as popular gemstones at the gemstone centre of Idar-Oberstein. Art Deco period witnessed extreme popularity of opals.

The history of Australian Opal dates millions of years ago, when parts of Australia were covered by a vast inland sea, and stone sediment was deposited along its shoreline. When the water masses flooded back, they flushed water containing silica into the resulting cavities and niches in the sedimentary rocks, and also the remains of plants and animals were deposited there. Slowly the silica stone transformed into Opal, for basically Opals are simply a combination of silica and water. Or, to be more precise: Opals are a gel from silica, with varying percentages of water.

In order to best bring out the play of color in a Fine Opal, the stones are usually cut and polished to round or oval cabochons, or any other softly domed shape, depending on the raw material. Only the best qualities of Fire Opal are suited to faceting.

Opal experts’ lingo :

When Opal experts talk about “harlequin”, “church windows” or “needle fire”, it is usual. They are terms describing Opals. The play of color in this stone is described with many imaginative terms for various structures and phenomena, like, for example, “flame opal”, “lightning and peacock opal”, or the above named “harlequin” and “church window”.

Black Opal or Opal with a dark grey body shows the most brilliant play of colors imaginable. Crystal opal, which comes immediately after Black Opal in the list, should be more transparent with a deep play of colors. White or milky Opals show more diffuse colors and are the least expensive Opals. The region specific characteristics include, for instance, denominations such as “Black Opal from Lightning Ridge” (the tops) or “Mexican Fire Opal”.

For evaluating Opals the thickness of the Opal layer is considered, the beauty of the patterning, the cut, weight and finish. Finally the overall impression will be decisive, and of course offer and demand determine how much you will have to pay for a specific Opal.