The stone encyclopedia
The world of precious & luxury stones
Gemstones, decorative stones and rare minerals, explained with the care of a museum and the eye of a jeweler.
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Three worlds of stone
From a one-carat ruby to a marble wall, every stone has a story. Start with the world that interests you.
Gemstones
Precious, semi-precious, rare collector stones and organic gems such as pearl and amber.
Decorative Stones
Marble, granite, onyx and quartzite: the luxury stones of architecture and interiors.
Crystals & Minerals
Carving stones, crystal specimens and unusual finds, from jade to meteorites.
Featured stones
The icons of the gem world
Alexandrite
Chrysoberyl · Hardness 8.5 Extremely RareDiamond
Diamond (carbon) · Hardness 10 UncommonEmerald
Beryl · Hardness 7.5–8 RareOpal
Opal (hydrated silica) · Hardness 5.5–6.5 UncommonPearl
Aragonite and conchiolin (nacre) · Hardness 2.5–4.5 UncommonRuby
Corundum · Hardness 9 RareSapphire
Corundum · Hardness 9 RareTanzanite
Zoisite · Hardness 6–7 RareBrowse by color
Find a stone by its color
Many stones come in more than one color. Sapphire alone appears in almost every shade except red.
Did you know?
Stones with surprising stories
Ruby and sapphire are the same mineral. A trace of chromium is what turns corundum red.
Read about rubyMichelangelo carved his David from a single block of marble quarried near Carrara.
Read about Carrara marbleDecorative stone spotlight
Calacatta Marble, the marble of luxury interiors
Quarried high in the Apuan Alps above Carrara, Calacatta is prized for its bright white background and bold, dramatic veining. It is far rarer than ordinary Carrara marble.
- Type
- Metamorphic
- Origin
- Carrara, Tuscany, Italy
- Best for
- Feature walls, kitchen islands, bathrooms
Birthstone of the month
November
November has two birthstones in warm golden tones. Topaz is one of the hardest silicate minerals, while citrine is a golden variety of quartz that is rare in nature.
Editorial standards
Written and fact-checked by the Tavira Gems Editorial Team
GIA Gem Encyclopedia·Smithsonian·USGS·Mindat
Our articles are researched using respected sources including these, and updated when new information appears. How we research