MINERALOGY · 52 GUIDES

Fifty-two minerals, one guide at a time.

Mohs hardness, crystal system, color range — from mineralogy references.

Fine ruby gemstone demonstrating vivid red characteristic of top-grade stones

Guide #037pigeons-blood-ruby.jpg

Pigeon's Blood Ruby

Light
Water—

Princess-cut diamond showing square outline with pointed corners and brilliant-style faceting

Guide #038princess-cut.jpg

Princess Cut

Light
Water—

Rhodolite garnet specimen showing characteristic rose-red to purplish colour

Guide #039rhodolite-garnet.jpg

Rhodolite Garnet

Light
Water—

Cut gemstone; rose cut features a flat base with domed triangular facets converging at an apex

Guide #040rose-cut.jpg

Rose Cut

Light
Water—

Faceted ruby gemstone showing characteristic red colour

Guide #041ruby.jpg

Ruby (Red Corundum)

Light
Water—

Blue sapphire gemstone specimen showing characteristic cornflower-blue colour

Guide #042sapphire.jpg

Sapphire

Light
Water—

Blue sapphire crystal showing characteristic vivid blue corundum representing September's birthstone

Guide #043september-birthstone.jpg

September Birthstone

Light
Water—

Red spinel crystal showing characteristic octahedral form and vivid colour

Guide #044spinel.jpg

Spinel

Light
Water—

Corundum specimen; star sapphire is corundum with oriented rutile silk producing six-rayed asterism

Guide #045star-sapphire.jpg

Star Sapphire

Light
Water—

Faceted gemstone showing step-cut facet arrangement with parallel tiers

Guide #046step-cut.jpg

Step Cut

Light
Water—

Faceted tanzanite gem showing blue-violet colour characteristic of the Merelani deposit

Guide #047tanzanite.jpg

Tanzanite

Light
Water—

Orange-yellow imperial topaz crystal from Ouro Preto, Brazil

Guide #048topaz.jpg

Topaz

Light
Water—