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Learn About Opals

 "the Queen of gems"

             - Shakespeare

Many people wonder, which is the best opal?

Like all precious gemstones, opals are valued by the same criteria: clarity, cut, colour and size. However, with an opal, colour is of most importance. The majority of the colours of the rainbow are found in precious rare and highly valued opal. Harlequin pattern (symmetrical square) is very rare and very valuable. Choose the colour you like - as "beauty is in the eye of the beholder".

Opal classification

Opal is a gemstone consisting of hydrated amorphous silica with the chemical formula SiO2.nH20. Opal is derived from the Greek word Opallos, meaning to see a change of colour, is a formation of non-crystalline silica gel. Millions of years ago, this gel seeped into the crevices and cracks of the sedimentary strata. Through eons of time and through natures heating and moulding processes, the gel hardened and can be found today in the form of brilliant opals.

 

Precious (solid) opalised fossils

The Australian opal fields situated in what are now semi-desert regions, were at one time under the ancient, vast inland sea that covered most of central Australia. Natural opalised fossils are occasionally unearthed and include: Opalised wood, seashells, mussels, fish, skeletons of giant marine reptiles, belemnites and plant stems. Polished and left in their natural form, with brilliant colour these fossils are rare and very valuable if authenticated. Only a few fossils are found in full shape and colour and are sought after by collectors and investors.

Precious (solid rock) light opal

The family of opal which shows a play of colour within or on a light body tone, such as milky with opaque pink colours and crystal, which is transparent with brilliant colours.

Precious (solid) black/dark opal

The family of opal with a play of colour within or on a black body tone. The darker the background the more the colour is naturally enhanced.

Boulder opal

Mined in Queensland where ironstone boulders occur within thin vein-lets of coloured opal running through the host rock. The solid opals are cut where the colour is dominant, with the natural ironstone left as background.

Andamooka Matrix

A natural porous opal rock with colour. Solid stones are cut, polished and placed in a sugar and sulphuric acid solution. The sugar carbonizes turning the opal black illuminating the natural opal colours into brilliant gems, similar to black opal. Andamooka in South Australia is the only field that produces small quantities of matrix.

Doublet

Two pieces of opal joined together. When mined opals are sometimes thin but brilliant in colour, thus to make them safe, they are cut, polished and glued onto a bad, usually potch opal (opal with no colour). Not recommended to immerse in water.

Triplet

Three layered, consisting of thin slices of opal affixed onto a piece of black glass, with a dome of quartz on the top. Do not immerse in water.

Synthetic opals (or Gilson opals) have no value, as they are man-made. We only stock natural opals.

Precious opal exhibits a play of colour, which is produced by the diffraction of light through a structure of spheres of silica. Common and potch opal does not exhibit a play of colour.

Opal is a treasure, a magical looking glass, which lets us see rare beauty of nature's own fireworks. Opal is not unlucky, does not shrink, or loose its colour. Please treat your opal with the care it deserves, making sure not to drop or hit it on hard surfaces.