Description and information about Opal Brightness and Patterns from Lightning Ridge Australia :
An Opal Brightness Scale assists in assigning a value to how bright an Opal is to the naked eye.
B5 being the Brightest and B1 being the Dullest.
On the left is just some of the patterns you might find in an Australian Opal. The names of the patterns are not a perfect science, as people will have a different perspectives on what to call a certain pattern.
The main patterns are , Pinfire, Floral, Flagstone, Ribbon, Broad Flash, Ribbon, Rolling Mackerel and Harlequin.
Then there secondary names such as, Chinese Writing, Rainbow, Peacock, Gem ect......
It's by mixing and matching that you may come to an accurate description of a pattern.