The Encyclopedia

Every Gemstone,
Documented.

Alexandrite gemstone

Alexandrite

Chrysoberyl · Mohs 8.5

'Emerald by day, ruby by night.'

Amethyst gemstone

Amethyst

Quartz · Mohs 7

The most prized variety of quartz.

Aquamarine gemstone

Aquamarine

Beryl · Mohs 7.5–8

The colour of clear ocean water.

Chrysoberyl gemstone

Chrysoberyl

Chrysoberyl · Mohs 8.5

The third-hardest gem - host to alexandrite and cat's-eye.

Citrine gemstone

Citrine

Quartz · Mohs 7

Quartz in the colour of autumn light.

Diamond gemstone

Diamond

Native element (carbon) · Mohs 10

The hardest natural substance on Earth.

Emerald gemstone

Emerald

Beryl · Mohs 7.5–8

Beryl coloured by chromium and vanadium - the green of empires.

Iolite gemstone

Iolite

Cordierite · Mohs 7–7.5

The 'Viking compass' - strongly pleochroic blue.

Lapis Lazuli gemstone

Lapis Lazuli

Rock (lazurite + calcite + pyrite) · Mohs 5–6

The blue of pharaohs and Renaissance painters.

Moonstone gemstone

Moonstone

Feldspar (orthoclase / albite) · Mohs 6–6.5

Adularescence - a moonlit glow that drifts across the gemstone.

Morganite gemstone

Morganite

Beryl · Mohs 7.5–8

Pink beryl - the gentle sister of emerald and aquamarine.

Opal

Hydrated silica · Mohs 5.5–6.5

A play of colour from microscopic silica spheres.

Peridot gemstone

Peridot

Olivine · Mohs 6.5–7

The only gem found in meteorites.

Ruby

Corundum · Mohs 9

The king of gems - corundum coloured by chromium.

Sapphire gemstone

Sapphire

Corundum · Mohs 9

Corundum in every colour but red.

Spinel gemstone

Spinel

Spinel group · Mohs 8

Mistaken for ruby for centuries - now collected on its own merits.

Tanzanite gemstone

Tanzanite

Zoisite · Mohs 6.5–7

Found in only one place on Earth.

Topaz

Topaz · Mohs 8

Hard and brilliant, with a perfect cleavage that demands respect.

Tourmaline gemstone

Tourmaline

Tourmaline group (elbaite, dravite, schorl…) · Mohs 7–7.5

The most colour-diverse gem species on Earth.

Tsavorite Garnet gemstone

Tsavorite Garnet

Garnet group (almandine, pyrope, spessartine, grossular andradite, uvarovite) · Mohs 6.5–7.5

A family of gems, not a single species.

Zircon gemstone

Zircon

Zircon · Mohs 6–7.5

High dispersion and brilliance - not to be confused with cubic zirconia.