Production
The original manufacturing process for goldstone was invented in seventeenth-century Venice by the Miotti family, which was granted an exclusive license by the Doge. Urban legend says goldstone was an accidental discovery by unspecified Italian monks or the product of alchemy, but there is no pre-Miotti documentation to confirm this.
The most common form of goldstone is reddish-brown, containing tiny crystals of metallic copper that require special conditions to form properly. The initial batch is melted together from silica, copper oxide, and other metal oxides to chemically reduce the copper ions to elemental copper. The vat is then sealed off from the air and maintained within a narrow temperature range, keeping the glass hot enough to remain liquid while allowing metallic crystals to precipitate from solution without melting or oxidizing.
After a suitable crystallization period, the entire batch is cooled to a single solid mass, which is then broken out of the vat for selection and shaping. The final appearance of each batch is highly variable and heterogenous. The best material is near the center or "heart" of the mass, ideally with large, bright metal crystals suspended in a semitransparent glass matrix.
Read more about this topic: Goldstone (gemstone)
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