Goldstone

Although goldstone is often mistaken for or misrepresented as a natural material, it is actually an attractive type of glittery glass. The classic orange-brown colored variety is made by heating molten glass to a temperature that is hot enough to dissolve granules of copper oxide that are added to the melt. When the copper oxide is completely dissolved, the melt is cooled very slowly, giving copper ions in the melt enough time find one another and grow into octahedral-shaped copper crystals. The bright metallic luster of these copper crystals is what causes the sparkling appearance and color of goldstone. Other varieties of goldstone are made using compounds of metals other than copper. The color of these goldstones is caused by the color of the glass, rather than the color of the reflections from the metallic crystals. The blue variety is caused by adding cobalt, the purple by adding manganese, and the green by adding chromium.