The opals
Gemmological information
Varieties of opals
Gems care
Virtues of opals
History and legends
The names which make up the galaxy of opals are many and are often difficult to interpret. The numerous varieties of opals are classified based on the presence or lack of the colour effect, the tint and tone of the base colour, and the geometry of the colour effect. The common opal is generally opaque, with no colour effect and is relatively widespread.

The noble opal in its finest variations is extremely rare and shows clear colour effect. Beauty and rarity make it a true gem.
Australian white opal: from translucent to semi-translucent with a colour effect on a white background.
Australian semi-black or grey opal: from translucent to opaque with colour effect on a clear to medium grey background.
Australian crystal opal: from transparent to semi-transparent with colourless base or of any shade with clear tone and colour effect.
Australian black crystal opal: from transparent to semi-transparent with dark base colour and colour effect.
Australian semi-crystal opal: from semi-transparent to translucent, with colour effect.
Water opal or Mexican Jelly: from transparent to semi-transparent, normally with colourless base colour and sufficiently variable colour effect.
Mexican fire opal: from transparent to semi-transparent with yellow to red body (it can have a brown component which is more or less visible): with or without colour effect; is also called Mexican opal, golden opal and sun opal.
The following varieties are available on request:
Australian black opal: from translucent to opaque with colour effect on a background of black, dark grey, blue, green, brown and other dark tones.
Mexican contra-luz opal: is a very rare type of opal which has a strong colour effect both in reflected and conducted light.
Australian boulder opal: a subtle class of opal with colour effect which you find in a matrix of iron minerals; the opal is cut in such a way as to keep the iron mineral as a base to increase durability and provide a dark background.
Australian matrix opal: subtle classes or marks of opal with a colour effect distributed in a non-uniform way in the matrix; also called mass opal.
Mexican cantera opal: variety with matrix often with a very lively colour effect.