Antique & vintage goldstone jewelry

THE ALLURE OF GOLDSTONE

Goldtone is a specially treated glass which is classified as a man-made gemstone because of its inclusion of copper. Earliest factual evidence places its invention on the island of Murano, near Venice, Italy in the seventeenth century by Vincenzo Miotti, who was granted exclusivity in its production. The secret recipe was guarded by the Miotti family for centuries.

The materials involved are quite inexpensive, but, there is a lot of finness in achieving a dense and even blend in the goldstone mix, necessary for its characteristic sparkle. By the 19th century, the process was independently rediscovered by French chemists. The Miotti family had also quit glass production and their methods were divulged. In the 1870s, goldstone was selling for $5 to $15 per pound, depending on quality.

Brown goldstone is the most common color. This type of glass is achieved by the addition of copper salts and iron oxide to the glass-making process. The liquid glass is left to cool very slowly with little oxygen, turning the copper salts to metallic copper.

Here is the recipe of the 19th century French chemist Pelouze:
"It is obtained by melting together 250 parts sand, 100 parts carbonate of soda, 50 parts carbonate of lime, and 40 parts bichromate of potassium. It will be seen that by this formula the spangles with a basis of copper are replaced by spangles with a basis of chrome."  (Dieulafait, 1876)

Other colors of goldstone sometimes seen are blue, purple, green or red. These are achieved by using colored glass or metals other than copper. Since goldstone is a type of glass, which can be molded in many shapes, it is ideal for jewelry making. Currently most goldstone is made in China. (D.H.)

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