Cultured pearls can be distinguished from natural pearls by X-ray examination. Nucleated cultured pearls are often 'pre-formed' as they tend to follow the shape of the implanted shell bead nucleus. Once the pre-formed beads are inserted into the oyster, it secretes a few layers of nacre around the outside surface of the implant before it is removed after six months or more.
Precious Fire Obsidian 48 x 38 mm. 134 cts. Precious Fire obsidian is a material which only occurs on Glass Buttes in central Oregon. It has extremely thin layers of minerals which break up light into spectacular, shifting colors. This material is not the same as "rainbow" obsidian, or other sheen obsidians. Recently, some doublet and triple stones have hit the market which incorporate a layer of Paua abalone shell to imitate the effect.