2027 Forecast

Gemstone reference

43 stones with composition, hardness, crystal system and origin — plus what each is traditionally used for.

Gemstone Guide: Every Stone, Its Composition and Hardness

How hard is each gemstone?

All 43 stones of the reference on the Mohs scale
All 43 stones of the reference on the Mohs scaleMohs scale from talc (1) to diamond (10) with every stone in the reference as a dot at the midpoint of its hardness range.Garnet: Mohs 6.5–7.5Amethyst: Mohs 7Citrine: Mohs 7Rose Quartz: Mohs 7Clear Quartz: Mohs 7Smoky Quartz: Mohs 7Aquamarine: Mohs 7.5–8Emerald: Mohs 7.5–8Bloodstone: Mohs 6.5–7Peridot: Mohs 6.5–7Sardonyx: Mohs 6.5–7Zircon: Mohs 6–7.5Carnelian: Mohs 6.5–7Onyx: Mohs 6.5–7Agate: Mohs 6.5–7Tiger's Eye: Mohs 6.5–7Aventurine: Mohs 6.5–7Diamond: Mohs 10Pearl: Mohs 2.5–4.5Alexandrite: Mohs 8.5Moonstone: Mohs 6–6.5Labradorite: Mohs 6–6.5Pyrite: Mohs 6–6.5Ruby: Mohs 9Sapphire: Mohs 9Spinel: Mohs 8Topaz: Mohs 8Opal: Mohs 5.5–6.5Rhodonite: Mohs 5.5–6.5Tourmaline: Mohs 7–7.5Turquoise: Mohs 5–6Lapis Lazuli: Mohs 5–6Hematite: Mohs 5–6Tanzanite: Mohs 6–7Jade: Mohs 6–7Obsidian: Mohs 5–5.5Malachite: Mohs 3.5–4Amber: Mohs 2–2.5Selenite: Mohs 2Fluorite: Mohs 4Sodalite: Mohs 5.5–6Kyanite: Mohs 4.5–7Lepidolite: Mohs 2.5–31Talc2Gypsum3Calcite4Fluorite5Apatite6Orthoclase7Quartz8Topaz9Corundum10Diamondfingernail 2.5window glass 5.5household dust (quartz) 7Source: Mohs scale minerals · ranges from our 43-stone referenceastrohot.com
All 43 stones of the reference on the Mohs scaleMohs scale from talc (1) to diamond (10) with every stone in the reference as a dot at the midpoint of its hardness range.1Talc2Gypsum3Calcite4Fluorite5Apatite6Orthoclase7Quartz8Topaz9Corundum10Diamondfingernail 2.5glass 5.5dust 7Source: Mohs scale minerals · ranges from our 43-stone referenceastrohot.com

Only 14 of the 43 stones are 7 or harder across their whole range, out of reach of household dust. Hardest: Diamond 10, Ruby 9, Sapphire 9. Softest: Selenite 2, Amber 2–2.5, Lepidolite 2.5–3.

Every stone at a glance

Stone Color Mohs System Chakra
Agate Banded, in almost any color 6.5–7 Trigonal Varies by variety
Alexandrite Green in daylight, red under incandescent light 8.5 Orthorhombic Heart, Crown
Amber Golden yellow to deep orange-brown 2–2.5 Amorphous Solar Plexus, Sacral
Amethyst Pale lilac to deep purple 7 Trigonal Third Eye, Crown
Aquamarine Pale blue to blue-green 7.5–8 Hexagonal Throat
Aventurine Green, also blue, peach, gray 6.5–7 Trigonal Heart
Bloodstone Dark green with red spots 6.5–7 Trigonal Root, Heart
Carnelian Orange to reddish brown 6.5–7 Trigonal Sacral
Citrine Pale yellow to amber brown 7 Trigonal Solar Plexus
Clear Quartz Colorless, transparent 7 Trigonal All, particularly Crown
Diamond Colorless, also yellow, brown, blue, pink 10 Cubic Crown
Emerald Green to bluish green 7.5–8 Hexagonal Heart
Fluorite Purple, green, blue, yellow, often banded 4 Cubic Third Eye, Heart
Garnet Deep red to orange, green, purple 6.5–7.5 Cubic Root
Hematite Metallic silver-gray to black 5–6 Trigonal Root
Jade Green, also white, lavender, black 6–7 Monoclinic Heart
Kyanite Streaky blue, also green, black, orange 4.5–7 (varies by direction) Triclinic Throat, Third Eye
Labradorite Gray with blue, green and gold flashes 6–6.5 Triclinic Third Eye, Throat
Lapis Lazuli Deep blue with gold pyrite flecks 5–6 Cubic (lazurite) Third Eye, Throat
Lepidolite Lilac to pinkish purple, often micaceous and flaky 2.5–3 Monoclinic Third Eye, Crown
Malachite Banded bright and dark green 3.5–4 Monoclinic Heart, Solar Plexus
Moonstone White to gray with blue sheen 6–6.5 Monoclinic Sacral, Third Eye
Obsidian Black, sometimes with sheen or snowflake patterning 5–5.5 Amorphous Root
Onyx Black, or black banded with white 6.5–7 Trigonal Root
Opal White, black or transparent with spectral flashes 5.5–6.5 Amorphous Crown, Heart
Pearl White, cream, pink, gray, black 2.5–4.5 Orthorhombic (aragonite) Sacral, Crown
Peridot Yellow-green to olive 6.5–7 Orthorhombic Heart, Solar Plexus
Pyrite Brassy metallic yellow 6–6.5 Cubic Solar Plexus
Rhodonite Rose pink with black manganese veining 5.5–6.5 Triclinic Heart
Rose Quartz Pale pink to rosy 7 Trigonal Heart
Ruby Red to purplish red 9 Trigonal Root, Heart
Sapphire Blue, also pink, yellow, green, colorless 9 Trigonal Throat, Third Eye
Sardonyx Banded reddish brown and white 6.5–7 Trigonal Root
Selenite Translucent white to colorless 2 Monoclinic Crown
Smoky Quartz Pale gray-brown to near black 7 Trigonal Root
Sodalite Royal blue with white veining 5.5–6 Cubic Third Eye, Throat
Spinel Red, pink, blue, purple, black 8 Cubic Root, Heart
Tanzanite Violet blue to deep purple 6–7 Orthorhombic Third Eye, Crown
Tiger's Eye Golden brown with a shifting band of light 6.5–7 Trigonal Solar Plexus, Root
Topaz Colorless, blue, yellow, imperial orange-pink 8 Orthorhombic Solar Plexus, Throat
Tourmaline Every color; often several in one crystal 7–7.5 Trigonal Varies by color — black for Root, pink for Heart
Turquoise Sky blue to green, often with dark matrix veining 5–6 Triclinic Throat
Zircon Blue, golden, red, green, colorless 6–7.5 Tetragonal Root, Crown

How to read the Mohs scale

Mohs hardness measures scratch resistance, not toughness. It runs from talc at 1 to diamond at 10, and the steps are not even — diamond is roughly four times harder than corundum at 9, which is itself twice as hard as topaz at 8.

The number that matters most in practice is 7. Airborne dust is largely quartz, which sits at 7, so anything softer will gradually dull from nothing more than being in a room. That goes a long way to explaining why opal rings lose their polish and sapphire rings do not.

Hardness also says nothing about breaking. Diamond tops the scale and will still split cleanly if struck along a cleavage plane, while jade — much softer — is among the hardest stones to break because its fibers interlock.

Storing stones so they do not scratch each other

One rule covers most damage: never store stones loose together. Diamond at 10 on the Mohs scale scratches everything else, sapphire and ruby at 9 scratch almost everything, and quartz-family stones at 7 will mark opal, turquoise, pearl and malachite. Keep each piece in its own pouch or a divided box, and put soft or porous stones — pearl, opal, turquoise, amber, malachite, selenite — away from perfume, heat and water.

Why many stone pages quote Pliny the Elder

Pliny the Elder wrote his Natural History in the 70s AD and died in the eruption of Vesuvius in 79. Its last books, on minerals and gemstones, are the fullest account of stones to survive from Roman times, and they draw on the Greek writer Theophrastus and other earlier authors. Pliny’s names do not always match ours — his topazos was peridot, his sapphiros lapis lazuli — so each quotation on a stone page says which modern stone it refers to.

What is measured and what is tradition

Composition, crystal system, hardness and origin on each stone page are mineralogical facts that can be checked. The chakra, element and meaning attached to a stone are cultural associations, mostly from modern crystal-healing books and older lapidaries, and they are not claims about physical effects. Each page keeps the two apart so you can read the folklore as folklore.

Cite this page

AstroHot. “Gemstone Guide: Every Stone, Its Composition and Hardness.” Accessed October 31, 2026. https://astrohot.com/crystals/gemstones/

For Wikipedia {{cite web |title=Gemstone Guide: Every Stone, Its Composition and Hardness |url=https://astrohot.com/crystals/gemstones/ |website=AstroHot |access-date=2026-10-31}}