AUSTRALIAN OPALS

Opal comes from the Greek word 'Opallos' meaning “to see a change (of colour)”. An Opal is a crystalline silica gel formation which seeped into stone crevices 15-30 million years ago and through the effects of heat and pressure hardened to form a magnificent multi coloured gem. The colourful display is the result of light passing through an array of minute tightly packed spheres of silica that refract at different angles into the colours of the spectrum. The size of the spheres determines what colour displays at the surface; the larger being less common and reflecting the red end of the spectrum. Opals displaying red play of colour are rare and regarded as more valuable.

Australia is home to 95% of the world’s total Opal production. However, the amount of Opal found is infinitesimal by comparison with our gemstones. For this reason, the rarity of the Opal is much greater than is generally appreciated.

What Factors Determine an Opal’s Value?

There are four factors that determine the value of an opal:

Generally black (or dark) opal is regarded as the rarest and most precious variety followed by boulder and light (with the exception of the crystal variety). The greater the range of spectral colours visible the more precious the opal ie: an opal displaying violet through to red is rarer than one only showing blue – green colours. There are several different patterns including the harlequin and pinfire that are the most sought after varieties.

BOULDER OPAL

Found in deposits in central Queensland this type of opal forms in seams through the middle of ironstone boulders. As it is only a thin layer, the opal is cut away with a layer of the host ironstone on the back in order to preserve the colourful precious material. This type of opal is most commonly cut into freeform shapes and most commonly displays vibrant green – blue colours on a dark background. Boulder opal stones can be quite large in size and are particularly suited to asymmetrical pendant and earring designs.

LIGHT OPAL

Light (or white) opals are those which show a play of colour through a light or white translucent background. It more commonly displays more delicate shades of pink, orange and green. Today, it is mined at Andamooka in the South Australian opal fields. The most precious of the light varieties is the ‘crystal’ light opal that is transparent and colourless with flashes of the spectral colours visible.

BLACK OPAL

The most famous of all Australian gemstones, the black opal is of special significance to our company and is woven deeply into the history and tradition of Percy Marks.

Discovered in the hot, dry hills of Lightning Ridge in outback New South Wales at the beginning of this century the black opal was almost doomed to obscurity until the young jeweller, Percy Marks fell under the mystical spell of this fiery colourful stone.