Diamonds are made of a crystalline form of pure carbon, creating the hardest mineral known. They have a high surface ‘lustre’, meaning that much light is reflected from their surface. This light is combined with light reflected through the stone from the back facets to create ‘brilliance’. Light passing through the stone is also split into a broad spectrum of colours termed ‘fire’. A modern brilliant-cut diamond is faceted so that it combines a high level of brilliance with fire.
Diamonds occur naturally in a variety of colours: colourless, yellow, brown, black, blue, green, pink and extremely rarely red. This ring is an unpolished, green diamond crystal. It is shaped like an octahedron, with eight faces and six points. It resembles two pyramids fused together at the base.
Eight diamond rings (Museum nos 1172 to 1179-1869) came to the V&A as part of a bequest of gemstones by the Reverend Chauncy Hare Townshend. The coloured diamonds had previously been in the famous collection of Henry Philip Hope. They entered the Museum in 1869. They have attracted the attention of gemmologists because it is known that their colours have not been enhanced or created by techniques invented after that date.