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The different classes & types of opal

There are many different classes and types of opal, each beautiful and unique in its own respect. Amongst the most distinguished are the black opal, the boulder opal and the light opal.

Black and dark opal: This is an opal which has a black or dark body colour when viewed from above. It is the rarest and most valuable opal variety.

Boulder opal: This type of opal forms naturally within the iron stone host rock and often only as a thin vein of precious opal. The opal usually has a baroque wavy surface and is often irregular in shape.

Light opal: This makes up the bulk of most precious opals, with brilliant light opals being extremely valuable. The transparent crystal variety of opal generally commands the highest price.


GDA™ Opal Grading

Class: The grade awarded for each opal
Class: Black, Grey, White, Crystal & Boulder

Grade Classifications Awarded for each Type
within each Class: Black, Dark and Light Opal  
AAA+ Exceptional Gem Quality
AAA   Superior Gem Quality
AA+    Fine Gem Quality
AA      Top quality Gem Grade
A+       Top quality Grade

GDA™ is proudly supported by:
Opal Producers Australia Limited