Gems and their copies: Part I

Most gemstones have been imitated in some way at some time over the centuries, Turquoise, pearls, garnets, diamonds, all have been copied. These copies might be made of glass, be created out of something specially made or might be achieved through using a similar but cheaper gemstone.

Glass has been used to imitate turquoise, pearls, opals, diamonds, rubies, emeralds, rubies – so many. One interesting glass from the late 18^th century to the late 19th century is opaline glass. Used for bottles, vases and boxes, it was also used in jewellery. The glass is an opaque to semi opaque stone originally made from adding bone ash to lead crystal. This resulted in a milky white semi opaque glass with flashes of colour like an opal, leading to its name. Other early colours were turquoise blue, yellow and pink. Despite its name, opaline was used as a substitute for other gemstones including turquoise. The Georgian gold locket ring pictured below contains two blue cabochon opaline set into each ring shoulder.

Glass was also a key component in many doublets, that is, stones made with a gemstone top and a glass bottom. Doublets have been created since Roman times. The most common doublets today are probably opal doublets but there was a significant industry in the later 19^th century in Europe and in the USA in the 1930s which created garnet-topped doublets. A slice of almandine garnet was glued at high heat over a layer of coloured paste. Once the doublet has been set in jewellery, it can sometimes be difficult to identify the two layers, particularly as the top layer of the stone will test as being a garnet and may contain natural inclusions.

Another created stone is the Soude emerald which is made up of a clear top and bottom of rock crystal or paste with a middle layer of green adhesive. Today, soude emeralds may consist of synthetic spinel layers. There are, of course, other gemstones that have been copied as doublets.

References:

Jennifer Boles, ‘Antique Obsession: Opaline’, 29 June 2023, https://southernhomemagazine.com/2023/06/29/antique-obsession-opaline/https://southernhomemagazine.com/2023/06/29/antique-obsession-opaline/

R Webster, ‘Gems’, 6th edition