Garnets are a form of silicate mineral that have a vitreous (glass-like) or resinous (amber-like) lustre.
The name garnet is derived from the 14th century English word ‘Gernet’ meaning dark red and the French word ‘grenate’ and Latin ‘granatus’, meaning grain and seed.
The term garnet is typically used to describe the red variety due to their visual similarity with the seeds of pomegranate fruit.
There are over 20 species of garnets that vary in colour due to their different chemical composition. But each of these species share essentially the same crystal structure. Garnets used in jewellery are typically red, but other species range from pink, brown, yellow, orange, blue and even green. Green garnets, called Demantoid, are the most valuable variety and were first discovered in the Ural mountains in Russia, during the mid 1800s. In the 1880s Peter Carl Faberge, the famous Imperial jeweller to the Russian royal family, embraced the native gemstone in his lavish jewels.
Garnets have a hardness rating of 6-7.5 on the Mohs scale. Almandine, is a harder variety which is not used in jewellery, but is instead used in abrasives for cutting steel. Red garnets have been used in jewellery since antiquity. A 5000 year old garnet bead necklace was founded in an Egyptian grave and during the 5-6th century garnets were frequently cut into cameos and intaglio rings.
In the 16-17th centuries the European jewellery market was flooded with garnets through the thriving trade from India, which is the main source of garnets. In the Renaissance large garnets were hollowed and the exterior polished into a smooth domed cabochon known as ‘Carbuncles’. Carbuncles were a common way of setting garnets to show off their rich colour. By having a thinner layer of garnet, more light could pass through and brighten stones that if solid would have been an almost black colour.
Magnets can be used to authenticate garnets as they have a pick up response to strong neodymium magnets.
