The special characteristic of these gems is their opalescence, a rainbow-like iridescence which (especially in rounded cut forms) change the angle of observation.

The electron-microscope, using a magnification of 20,000, reveals the cause: tiny sphered (0.001 of a millimeter in diameter) of the mineral crystallite layered in siliceous jelly cause the reflection or interference patterns.

Opal usually contains 4 to 9 percent water, but lower and much higher values have been observed. The contents of alumina, ferric oxide, and alkalis are variable but may amount to several percent in light-coloured opals and more if pigmenting minerals are also present. Precious opal has been synthesized. Opaline silica is a friable hydrous silica found near hot springs and geysers.

Color	All colors, partially opalescence
Refractive Index	1.37-1.52
Chemistry	Hydrous, Silicon dioxide
Hardness	5.5-6.5
Density	1.98-2.5
Crystal Group	Amorphous
Ocurrence	Australia, Czechoslovakia, Mexico

Opal is considered to be a black witchcraft stone. It is recommended to wear for those who were born in October. In the Middle ages opal rings were worn to save from plague. As a talisman opal brings luck in all matters and deeds but on one condition: the owner must be honest and not greedy. Opal is also considered to provide prophetic ability.

The pictures above only represents the general appearance of the Opal. Please note that the real Opals in our stock will be of varied shapes, color and sizes.