Goldstone

Hardness: 5-6 (Mohs scale), Color: Typically reddish-brown with sparkling inclusions (copper flecks), but also available in blue, green, and purple. Luster: Vitreous with metallic glitter due to copper. Crystal Structure: Amorphous (glass).

Goldstone is an artificial glass created in a low-oxygen reducing atmosphere. Tiny crystals of copper are introduced into a molten glass matrix, which then cool slowly to allow the copper to crystallize without oxidizing. The precise method of its invention is often attributed to the Miotti family of Venice, Italy, in the 17th century, though there may be earlier origins.

Primarily used in jewelry (beads, cabochons, carved ornaments) and decorative items due to its attractive sparkle. It is a popular, inexpensive alternative to natural sparkling gemstones.

The sparkle in Goldstone is known as 'aventurescence', mimicking the effect seen in natural minerals like Aventurine quartz. The earliest known production of Goldstone was in Venice, Italy, where it was called 'aventurine glass'. There are variations of goldstone made with different metals for the sparkle, such as cobalt (for blue goldstone) or chromium (for green goldstone).

Goldstone is not found in nature. It is identified by its consistent, evenly distributed internal glittering specks within a glassy matrix, often with a slightly rounded or polished form. The 'flecks' are typically copper, appearing as tiny, flat, reflective metallic platelets. Natural aventurine generally has a less uniform sparkle and may show other mineral inclusions. It is widely available globally in shops selling crystals, jewelry, and craft supplies.