Tumbled Red Goldstone

Though not a stone--or gold!--this manufactured "gemstone material" is known by many names: "aventurine glass," stellaria, gold star glass, monkstone or monk's gold. The final two names refer to the urban legend that goldstone was created accidentally by Italian monks in the 1600s. There are earlier samples, however, including a smooth amulet from Iran that dates to the 1100s to 1200s. The earliest written reference to the material we call goldstone, however, is Vincenzo Miotti of Venice being granted exclusive license by the Venetian head of state (the Doge) to create this sparkling opaque glass. It has been linked to the medieval art of alchemy almost from its creation. A deep red variation--called haematinum or purpurin--may have been made by the Romans, with the recipe getting lost during the Dark Ages.

Modern goldstone can be created either with copper flecks or with other metallic compounds such as cobalt, manganese or chromium oxide. These are used in goldstones made using colors (respectively) such as purple, blue and green.