"It is useful that the seller now includes a ruler in the photo for scale so that buyers will know how very tiny the pretty colored stones are. My order contained stones smaller than 1/4 inch. The stones are irregularly shaped with a slice of opal on the top which is glued to a black base to deepen the color of the thin opal and give it strength. When I ordered I didn't really know what a doublet was, so I recommend you Google the term if you have never seen one. They are probably useful for inlay work of some kind, but not for mounting in silver clay jewelry that is fired in the kiln, which is my specialty. Unfortunately, they were also too small to be prong set by me. Sadly, I had to return the stones. The seller was polite and worked with me to my satisfaction."
Natural Opal Doublet Cabochon Gemstone Mix Lot- Loose Multifire Opal Doublet Gems for Sale