While most patterns such as flashfire or broad flashfire have very little affect on the price of opals, there are patterns which can affect the price. The fire pattern is creative by the play of color on the stone. Patterns are infinately variable and no two are ever exactly the same. However, they can be generally catagorized.
Pinfire: Small pinpoint circles of fire. When viewed from the side, this pattern often looks like th side of a stack of pins, while the top view looks like the points of those pins, hence the name. The side view is called columnar fire. This is actually a fairly rare pattern. Many small flashfire pattern stones are incorrectly identified as pinfire. Additionally, many synthetic opals have this pattern.
Flashfire: Irregular splashes of fire covering the stone. The splashes of fire can be fiarly large, but no one area would cover more than 50% of the surface of the opal.
Broad Flashfire: Sheets of color usually covering a large section or the entire surface of the stone.
Rolling Flashfire: Sheets of color which roll accross the surface of the stone as it is moved. This type of pattern is almost impossible to photograph, but is highly prized.
Harlequin: Square-shaped sheets of color that fit together much like a checkerboard. To be considered true harlequin, the squares must be big enough to be seen at arms length.
Pattern text taken from Opal: Identification and value by Paul B Downing, Ph.D.
J. Thomson Custom Jewelers