This is the most dramatic and beautiful opal I have ever found. The play of color is incomparable. I suspect it may be boulder opal, and I can say for certain is it is not a doublet or triplet. Study it under a 20x loupe. Old compound opals always have dull edges from where moisture has seeped in between the layers. The patina on this is not chemical--it has been put away somewhere open to air for a long time. Areas that look gray at one angle, burst into color from another (thus all the pictures). The color flashes in sheets of full spectrum. Hanging in there is that mysterious black crescent moon made by mother nature. It measures 2 by 1 & 5/8 inches and is in excellent condition. Signed Stg. Sil. (different).