Gemstone glossary

A few terms that come up in the descriptions of the pieces, each explained in a sentence or two.

Padparadscha

A sapphire (corundum) in which pink and orange meet in a single stone. The name comes from Sinhalese and means “lotus colour”; its historic source is Sri Lanka.

Unheated

A stone that has had no heat treatment. Most sapphires are heated to improve their colour, so fine natural colour without heating is rarer.

Royal blue

A trade term for sapphire colour: a deep, saturated blue with a slight violet tint.

Star sapphire

Needle-like inclusions aligned inside the stone produce a six-rayed star under a single light when the sapphire is cut as a cabochon.

Cat’s-eye chrysoberyl

The chatoyant variety of chrysoberyl. A band of light moves across the cabochon; in the jewellery trade, “cat’s eye” on its own means this stone.

Mahenge spinel

Spinel from Mahenge in Tanzania, known for pinks and reds with an almost fluorescent glow.

Tsavorite

A green grossular garnet, mined mainly in the border region between Kenya and Tanzania.

Lagoon tourmaline

A tourmaline in a blue-green that recalls shallow tropical water; the trade calls the colour “lagoon”.

Sugarloaf cut

A cabochon with a nearly square base whose top rises into four curved faces, like an old sugarloaf.