Opal Pattern

The various patterns of the play-of-colour have their cause in stacking faults in the silica sphere structure of opal which may produce many distinct colour patches.

There are no limits to the fantasy of patterns mother nature has produced as little as to the different terms that have been and are being created by people with a vivid imagination...
Therefore it's no surprise, that these terms are sometimes misapplied or that some people use the same or similar terms but with different ideas.
Fortunately there are also some patterns that are more or less consistently used or clearly defined. We will limit our examples to such patterns and include some of the most important patterns as we do name them.

Mix of various patterns e.g. Broad flash and Pinfire	Pattern resembling the structure of moss	Similar to Broad flash but with diffuse, textured flashes	Separated, randomly sized and distributed patches
Mixed	Moss	Sheen	Flashfire

Many closely packed pinpoints of fire with columnar structure	Colour patches form more or less parallel running ribbons	Single large flash that covers a substantial part of the face	Long flash that rolls across the face when stone is moved
Pinfire	Ribbon	Broad Flash	Rolling Flash

Randomly oriented patches, broken by fine parallel lines	Pattern resembling the design of Chinese ideographs	Variously shaped patches, fitting mosaic-like together	Mosaic-like pattern, resembling a fish scale design
Chaff	Chinese Writing	Flagstone Harlequin	Fishscale Harlequin