Opal

The mineral opal is amorphous hydrated silica, its water content sometimes being as high as 30%. Being amorphous has no crystal form, occurring in its irregular veins and masses. It has concordat fracture, hardness 5.5-6.5, specific gravity 2.1-2.2, and a highly variable color. Opal ranges from colorless through white, milky blue, gray, red, yellow, green, and also brown and black. Often many of these colors could be seen at once, caused by interference from minute cracks in the opal which are normally filled with secondary silica and by thin lamellae formed inside the opal during its solidification. The term "opalescent" usually refers to this unusual and beautiful type of color.

Colour and Value

Besides the gemstone varieties, which show a play of colors, there are other kinds of common opal such as the milk opal (a milky bluish to greenish), resin opal (honey-yellow with a resinous luster), and wood opal (caused by the replacement of the organic material in wood with opal), Menilite (brown or grey), and also hyalite, a colorless glass-clear opal sometimes called as Muller's Glass.

Opal is a mineral gel that is deposited at relatively low temperature and could occur in the fissures of almost any kind of rock. The word opal comes from the Latin opals.

Nature’s entire splendor seems to be reflected in the manifold good opulence of fine Opals: fire and lightnings, all the colors of the rainbow and including soft shine of far seas. Australia is the classical country of its origin. Almost ninety-five per cent of all fine opals had come from the dry and remote outback deserts.

Numerous legends and tales surround this colorful gemstone that could be traced back in its origins to a time long before our memory, to the ancient dream time of Australian aborigines. It is reported in their legends, which creator came down to Earth on a rainbow, in order to bring this message of peace to all the humans. And at the very spot, where his foot touched the ground, this stones became alive and got started sparkling in all the colors of the rainbow. That was the birth of the Opals.

The group of fine Opals includes quite a number of wonderful gemstones that share one characteristic: they shine and sparkle in a continually change play of colors full of fantasy, which experts describe as “opalising”. Depending on its kind, place of occurrence, and colour of the main body, people may differentiate Dark and Black Opal, White or Light Opal, Milk or Crystal Opal, Boulder Opal, Opal Matrix, Yowah Nuts from Queensland – the so-called “picture stones“, and also Mexican and Fire Opal. Opal variations are practically unlimited. They all show in their own special way, which unique play of colors – except for Fire Opal that due to its transparency, however, is nevertheless also considered a Fine Opal specimen. If Opals are lacking the typical play of colour, they are simply known as “Common Opal”.