THE JGRL GEM LIBRARY

Get to know gemstones.
Discover the reasons for their beauty.

The structure behind a color. The place a gem formed. The cut that brings out its light.
A collection of fundamentals to help you understand each stone.

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20 GEMS

Crystals / Origins / Colors / Hardness / Cuts

Explore gemstones GEM INDEX Crystal structure CRYSTALS Hardness & durability DURABILITY Cutting fundamentals CUTTING

EXPLORE THE GEMSTONES

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Search by name or color to discover a gemstone.

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2 results of 20 gemstones

A gem with a hardness range may appear in more than one band.

Corundum

Ruby

The red variety of corundum, colored by chromium. Sapphire belongs to the same mineral species.

Mohs hardness: 9
Crystal system: Trigonal

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Corundum

Sapphire

Corundum in a wide range of colors, not only blue. Red corundum is classified separately as ruby.

Mohs hardness: 9
Crystal system: Trigonal

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Illustrations suggest color and shape. Individual stones vary; each gem page includes further details and references.

A LITTLE KNOWLEDGE, A DEEPER APPRECIATION

The more you know,
the more there is to discover.

How do hardness and toughness differ?
Understand the language of gems, one idea at a time.

Read gemstone fundamentals

Crystals & minerals

Ruby and sapphire are varieties of the same mineral.

Hardness & care

Mohs hardness indicates resistance to scratching.

Shape & cut

Oval describes a shape; brilliant describes a cutting style.