Mohs Hardness of Gemstones — Chart
Last updated: August 2026
Mohs hardness ranges (min–max) for 132 gemstone species, sorted hardest to softest. Includes cleavage and crystal system. Many species overlap on the scale — hardness brackets candidates; it rarely identifies a stone on its own.
Taking this reading yourself? The full identification sequence →
Common hardness lookups: Diamond 10 · Moissanite 9.25 · Sapphire 9 · Ruby 9 · Topaz 8 · Emerald 7.5–8 · Quartz 7 · Opal 5.5–6.5 · Pearl 2.5–4.5 · Amber 2–2.5 · Turquoise 5–6
The Mohs hardness scale ranks the relative scratch resistance of minerals from 1 (talc) to 10 (diamond). In gemology it serves as a quick screening test and as a durability guide for setting and wear. Diamond at 10 is the hardest known natural material; corundum (ruby and sapphire) at 9 is hard enough to scratch quartz; feldspar at 6 is scratched by a steel file. The scale is ordinal, not linear — the difference in absolute hardness between 9 and 10 (diamond vs. corundum) is far greater than between any adjacent pair lower on the scale.
In field identification, hardness tests should be used with caution. Scratching a faceted gem can damage it; testing on an inconspicuous area with a reference mineral or steel probe gives only a rough bracket. A better field application is knowing which gems are too hard to be scratched by common objects: a steel file (about 6.5) will scratch anything below 6.5; a quartz crystal (7) will scratch anything below 7. Gems below 7 (fluorite, apatite, calcite, amber, jet) require gentler handling and are more susceptible to abrasion in jewelry.
Some gem species show a range of hardness due to directional variation (cleavage direction vs. growth direction) or compositional variation within a species group. Kyanite, for example, is notably anisotropic: about 4.5 parallel to the length and 6–7 across it — which is exactly the 4.5–7 range this chart records for it. Overlap on the scale is the norm rather than the exception — 50 of the 132 species in this chart have a range that includes 7 — so a hardness bracket should always be combined with refractive index and specific gravity before calling a stone. The table below shows the full published range for each species.
Studying for the GIA or FGA practical? Loupewise drills hardness alongside RI and SG and runs timed mock exams built around the real exam formats.
Practice exams →| Gem | Mohs Hardness | Cleavage | Crystal System | Notes |
|---|---|---|---|---|
| Blue Diamond | 10 | Perfect | Cubic | Blue color in Type IIb diamonds is caused by trace boron. Natural Type IIb diamonds are… |
| Brown Diamond | 10 | Perfect | Cubic | Brown diamonds are the most abundant fancy color. Brown color arises from plastic… |
| Diamond | 10 | Perfect | Cubic | The hardest natural substance, known for its brilliance and fire. |
| Pink Diamond | 10 | Perfect | Cubic | Pink color in diamonds arises from plastic deformation of the crystal lattice creating… |
| Yellow Diamond | 10 | Perfect | Cubic | Yellow diamonds are Type Ia (Cape series, nitrogen in B-aggregates — most common natural… |
| Moissanite | 9.25 | None | Hexagonal | All gem-quality moissanite in trade is synthetic silicon carbide (SiC), grown by CVD.… |
| Color-Change Sapphire | 9 | None | Trigonal | Color-change sapphire is corundum colored by vanadium, shifting from blue or blue-gray in… |
| Padparadscha Sapphire | 9 | None | Trigonal | Pinkish-orange to orangey-pink corundum variety; color must show both pink and orange in… |
| Pink Sapphire | 9 | None | Trigonal | Pink sapphire is chromium-colored corundum with insufficient saturation to qualify as… |
| Ruby | 9 | None | Trigonal | Ruby is the red variety of corundum. Origin affects value and fluorescence: Burmese… |
| Sapphire | 9 | None | Trigonal | Sapphire is any color of corundum except red (ruby). Origin affects value and… |
| Star Ruby | 9 | None | Trigonal | Star ruby displays a 6-rayed star from three sets of rutile silk inclusions at… |
| Star Sapphire | 9 | None | Trigonal | Star sapphire displays a 6-rayed star from three sets of rutile silk inclusions. Blue and… |
| Synthetic Color-Change Corundum | 9 | None | Trigonal | Vanadium-doped synthetic corundum sold as 'alexandrite' in estate jewelry since the… |
| White Sapphire | 9 | None | Trigonal | White sapphire is colorless corundum. As a diamond simulant, its main weakness is very… |
| Yellow Sapphire | 9 | None | Trigonal | Yellow sapphire is iron-colored corundum (Fe³⁺). Sri Lankan and Burmese material often… |
| Alexandrite | 8.5 | Distinct | Orthorhombic | The color-change variety of chrysoberyl, appearing green in daylight and red in… |
| Cat's Eye Chrysoberyl | 8.5 | Distinct | Orthorhombic | Cat's eye chrysoberyl (cymophane) chatoyancy is caused by parallel growth tubes or rutile… |
| Chrysoberyl | 8.5 | Distinct | Orthorhombic | A durable gemstone known for its brilliance. The cat's eye variety (cymophane) shows… |
| Cubic Zirconia | 8–8.5 | None | Cubic | Cubic zirconia (ZrO2) is entirely synthetic — no natural gem-quality cubic ZrO2 exists.… |
| Taaffeite | 8–8.5 | None | Hexagonal | Taaffeite (BeMgAl₄O₈) was first identified as a new mineral species in 1945 after Count… |
| YAG | 8–8.5 | None | Cubic | YAG (Yttrium Aluminum Garnet, Y₃Al₅O₁₂) is a man-made material with no natural… |
| Aquamarine | 7.5–8 | Indistinct | Hexagonal | Aquamarine is the light blue to greenish-blue variety of beryl. |
| Black Spinel | 8 | None | Cubic | A hard, durable, and singly refractive gemstone often used as a simulant for black… |
| Emerald | 7.5–8 | Indistinct | Hexagonal | Emerald is the green to greenish-blue variety of beryl. |
| Goshenite | 7.5–8 | Indistinct | Hexagonal | Colorless beryl. Distinguished from quartz by higher RI and hardness; from white sapphire… |
| Heliodor | 7.5–8 | Indistinct | Hexagonal | The yellow to greenish-yellow variety of beryl, colored by iron (Fe³⁺). Also called… |
| Morganite | 7.5–8 | Indistinct | Hexagonal | The pink to orange-pink variety of beryl, colored by manganese. |
| Phenakite | 7.5–8 | Indistinct | Trigonal | Beryllium silicate with unexpectedly high RI for its light weight. Occasionally sold as a… |
| Red Beryl | 7.5–8 | Indistinct | Hexagonal | Red beryl (bixbite) is colored by Mn²⁺ and found almost exclusively in the Wah Wah… |
| Spinel | 7.5–8 | None | Cubic | A durable, singly refractive gemstone that occurs in a wide range of colors. |
| Synthetic Spinel | 8 | None | Cubic | Flame-fusion synthetic spinel was the dominant birthstone simulant from the… |
| Topaz | 8 | Perfect | Orthorhombic | A hard and durable gemstone available in a wide range of colors. |
| Almandine Garnet | 7–7.5 | None | Cubic | The most common garnet, known for its deep red to purplish-red colors. |
| Andalusite | 7–7.5 | Distinct | Orthorhombic | Strong trichroism (green, red-brown, yellow-orange) is the primary diagnostic; color… |
| Chrome Tourmaline | 7–7.5 | Indistinct | Trigonal | Chrome tourmaline is colored by Cr³⁺ rather than iron, producing a rich emerald-like… |
| Color-Change Garnet | 7–7.5 | None | Cubic | Pyrope-spessartite garnet with color change from blue-green or grey-blue in daylight to… |
| Danburite | 7–7.5 | None | Orthorhombic | Danburite is sometimes sold as a colorless diamond substitute or confused with colorless… |
| Grandidierite | 7–7.5 | Distinct | Orthorhombic | Grandidierite is an exceptionally rare borosilicate mineral from Madagascar displaying… |
| Green Tourmaline | 7–7.5 | Indistinct | Trigonal | Iron-bearing green tourmaline (verdelite) ranges from pale mint to deep forest green… |
| Grossular Garnet | 6.5–7.5 | None | Cubic | Grossular garnet ranges from colorless (leuco-grossular) to delicate mint green (Merelani… |
| Hessonite Garnet | 7–7.5 | None | Cubic | Grossular is a calcium-aluminium garnet; the orange-brown variety is called Hessonite.… |
| Indicolite | 7–7.5 | Indistinct | Trigonal | Blue to greenish-blue elbaite tourmaline. Separated from blue sapphire by much lower RI… |
| Iolite | 7–7.5 | Distinct | Orthorhombic | Famous for its extreme pleochroism, showing different colors when viewed from different… |
| Malaya / Umbalite Garnet | 7–7.5 | None | Cubic | Malaya (or Umbalite) garnet is a pyrope-spessartite solid solution from the Umba River… |
| Paraiba Tourmaline | 7–7.5 | Indistinct | Trigonal | Paraiba tourmaline (elbaite) derives its neon blue-green to blue color from copper and… |
| Pyrope Garnet | 7–7.5 | None | Cubic | Known for its fiery red color, pyrope is a member of the garnet group. |
| Rhodolite Garnet | 7–7.5 | None | Cubic | Pyrope-almandine solid solution (~2:1 ratio) with purplish-red to raspberry-red color. RI… |
| Rubellite | 7–7.5 | Indistinct | Trigonal | Saturated red to pink-red elbaite tourmaline. Key field separation from ruby: RI… |
| Spessartite Garnet | 7–7.5 | None | Cubic | Orange to reddish-brown garnet; the vivid orange variety from Namibia is commercially… |
| Star Garnet | 7–7.5 | None | Cubic | Star garnet is the asteriated variety of almandine, displaying a 4-rayed star from two… |
| Tourmaline | 7–7.5 | Indistinct | Trigonal | Elbaite tourmaline occurs in a wide range of colors with strong pleochroism. Named color… |
| Tsavorite Garnet | 7–7.5 | None | Cubic | The green, chromium or vanadium-rich variety of grossular garnet. |
| Watermelon Tourmaline | 7–7.5 | Indistinct | Trigonal | Watermelon tourmaline (elbaite) has a pink to red core surrounded by a green rim. The… |
| Zircon | 7.5 | Indistinct | Tetragonal | A brilliant natural gemstone with high dispersion, not to be confused with cubic zirconia. |
| Agate | 6.5–7 | None | Trigonal | Banded chalcedony variety. Natural agate is typically grey-white with muted banding… |
| Amethyst | 7 | None | Trigonal | The purple variety of quartz, its color is caused by iron impurities and irradiation.… |
| Ametrine | 7 | None | Trigonal | Bicolor quartz variety with zones of purple (amethyst) and yellow-orange (citrine) in a… |
| Aventurine | 7 | None | Trigonal | A macrocrystalline quartz aggregate with flat platy inclusions (typically fuchsite mica… |
| Bloodstone | 6.5–7 | None | Trigonal | Dark green opaque chalcedony with distinctive red, orange, or yellow spots from iron… |
| Carnelian | 6.5–7 | None | Trigonal | Orange-red to red-brown translucent chalcedony; color from iron oxide… |
| Cassiterite | 6–7 | Indistinct | Tetragonal | A tin oxide mineral that is the most important ore of tin, rarely seen as a gemstone. |
| Chalcedony | 6.5–7 | None | Trigonal | Microcrystalline quartz aggregate. Generic chalcedony is translucent blue, grey, or… |
| Chrysocolla Chalcedony | 6.5–7 | None | Trigonal | Chrysocolla finely dispersed through chalcedony, traded as "gem silica". The properties… |
| Chrysoprase | 6.5–7 | None | Trigonal | Apple-green to yellow-green chalcedony; color caused by nickel silicate inclusions.… |
| Citrine | 7 | None | Trigonal | The yellow to brownish-orange variety of quartz, often created by heat treating amethyst. |
| Demantoid Garnet | 6.5–7 | None | Cubic | The green variety of andradite garnet, prized for its exceptional brilliance and fire.… |
| Diaspore | 6.5–7 | Perfect | Orthorhombic | Color-change diaspore marketed as Zultanite or Csarite shifts from kiwi green in daylight… |
| Hawk's Eye | 7 | None | Trigonal | Blue-grey to blue-green chatoyant quartz formed where crocidolite asbestos is replaced by… |
| Hiddenite | 6.5–7 | Perfect | Monoclinic | Green chromium-bearing spodumene from North Carolina. True hiddenite (Cr-colored) is very… |
| Jadeite | 6.5–7 | Perfect | Aggregate | The rarer and more valuable of the two minerals known as jade. |
| Kunzite | 6.5–7 | Perfect | Monoclinic | The pink to lilac variety of spodumene, known for strong pleochroism and fluorescence. |
| Kyanite | 4.5–7 | Perfect | Triclinic | Blue aluminum silicate commonly confused with sapphire or tanzanite. Uniquely among… |
| Onyx | 6.5–7 | None | Trigonal | True onyx is a parallel-banded chalcedony with alternating black and white layers. In… |
| Peridot | 6.5–7 | Indistinct | Orthorhombic | Known for its distinctive olive-green color and strong birefringence. |
| Pietersite | 6.5–7 | None | Aggregate | Trade name for a brecciated aggregate of hawk's eye (blue crocidolite-replaced quartz)… |
| Prasiolite | 7 | None | Trigonal | Prasiolite is the pale green variety of quartz produced commercially by heat-treating or… |
| Rock Crystal | 7 | None | Trigonal | The colorless and transparent variety of quartz. |
| Rose Quartz | 7 | None | Trigonal | The pink variety of quartz, usually found in a massive, translucent form. The color in… |
| Sinhalite | 6.5–7 | Indistinct | Orthorhombic | Sinhalite is a rare borate mineral first described as a gem species in 1952 (originally… |
| Smoky Quartz | 7 | None | Trigonal | The brown to black variety of quartz, colored by natural irradiation of aluminum… |
| Tanzanite | 6–7 | Perfect | Orthorhombic | The blue to violet variety of zoisite, known for its striking trichroism. |
| Thulite | 6–7 | Perfect | Orthorhombic | Thulite is a manganese-bearing pink variety of zoisite used primarily in ornamental work… |
| Tiger's Eye | 7 | None | Trigonal | Chatoyant quartz formed by pseudomorphous replacement of crocidolite asbestos fibers with… |
| Amazonite | 6–6.5 | Perfect | Triclinic | Blue-green microcline feldspar colored by lead and water; frequently sold as a turquoise… |
| Benitoite | 6–6.5 | Indistinct | Hexagonal | Found almost exclusively in San Benito County, California, in association with neptunite… |
| Black Opal | 5.5–6.5 | None | Amorphous | Black opal from Lightning Ridge, NSW, Australia is commercially the most valuable opal… |
| Chrome Diopside | 5.5–6.5 | Perfect | Monoclinic | Vivid grass-green chromium-bearing diopside sourced primarily from Russia/Siberia.… |
| Fire Opal | 5.5–6.5 | None | Amorphous | Fire opal is the orange-to-red variety of opal from Mexico (principally Querétaro state)… |
| Hematite | 5.5–6.5 | None | Trigonal | An iron oxide with a high metallic luster and a characteristic red-brown streak. |
| Kornerupine | 6.5 | Indistinct | Orthorhombic | Rare borosilicate mineral from Madagascar, Sri Lanka, and Greenland. Green… |
| Labradorite | 6–6.5 | Perfect | Triclinic | Displays a spectacular iridescent effect known as labradorescence. |
| Moonstone | 6–6.5 | Perfect | Monoclinic | Characterized by a billowy, bluish-white light effect called adularescence. IMPORTANT… |
| Nephrite | 6–6.5 | None | Aggregate | A variety of actinolite-tremolite, known for its toughness and greasy luster. |
| Opal | 5.5–6.5 | None | Amorphous | Precious opal exhibits play-of-color from microscopic silica sphere diffraction. Common… |
| Prehnite | 6–6.5 | Distinct | Orthorhombic | Pale apple-green prehnite is common in estate jewelry as cabochons and beads, often… |
| Rainbow Moonstone | 6–6.5 | Perfect | Triclinic | "Rainbow moonstone" is a widely used trade name for white or colorless labradorite… |
| Rhodonite | 5.5–6.5 | Perfect | Triclinic | A manganese silicate known for its rosy pink color, often with black dendritic inclusions. |
| Scapolite | 6–6.5 | Distinct | Tetragonal | Yellow and violet scapolite appear in estate jewelry and at gem shows, sometimes confused… |
| Sugilite | 5.5–6.5 | Indistinct | Hexagonal | A rare cyclosilicate mineral found almost exclusively at the Wessels Mine in the Kalahari… |
| Sunstone | 6–6.5 | Perfect | Triclinic | A plagioclase feldspar (typically oligoclase or andesine) displaying aventurescence — a… |
| Charoite | 5–6 | Perfect | Monoclinic | A rare complex silicate mineral found only at the Murun Massif in Siberia. Named for the… |
| Clinohumite | 6 | Indistinct | Monoclinic | Clinohumite is a rare magnesium iron silicate of the humite group, only occasionally… |
| Hackmanite | 5.5–6 | Distinct | Cubic | Hackmanite is the tenebrescent variety of sodalite, a sodium aluminum silicate chloride… |
| Hauyne | 5.5–6 | Indistinct | Cubic | Hauyne (also spelled Haüyne) is a rare blue feldspathoid of the sodalite group, found… |
| Lapis Lazuli | 5–6 | Indistinct | Aggregate | A deep-blue metamorphic rock used as a semi-precious stone that is prized since antiquity. |
| Low-Type Zircon | 6 | None | Tetragonal | A type of zircon whose crystal structure has been damaged by radioactive elements. |
| Serpentine | 3–6 | None | Monoclinic | Serpentine is the most common jade simulant in the trade, sold as 'new jade', 'Korean… |
| Sodalite | 5.5–6 | Indistinct | Cubic | Opaque to translucent blue sodium aluminum silicate chloride; chemically distinct from… |
| Star Diopside | 5–6 | Distinct | Monoclinic | Black asteriated diopside from India displaying a 4-rayed star from two sets of magnetite… |
| Turquoise | 5–6 | None | Triclinic | An opaque, blue-to-green mineral that is a hydrated phosphate of copper and aluminum.… |
| Enstatite | 5–5.5 | Distinct | Orthorhombic | Chrome enstatite is a chromium-bearing orthorhombic pyroxene producing rich green color… |
| Moldavite | 5.5 | None | Amorphous | Tektite — natural glass formed ~14.8 million years ago by a meteorite impact in the Ries… |
| Obsidian | 5–5.5 | None | Amorphous | A naturally occurring volcanic glass formed when lava cools rapidly. |
| Sphene | 5–5.5 | Distinct | Monoclinic | Known for its exceptional dispersion which exceeds that of diamond, giving it incredible… |
| Apatite | 5 | Indistinct | Hexagonal | Neon blue-green apatite from Madagascar is often confused with paraiba tourmaline or… |
| Larimar | 4.5–5 | Perfect | Triclinic | The blue gem variety of pectolite, found only in the Los Chupaderos mine area of Barahona… |
| Pearl | 2.5–4.5 | None | Aggregate | An organic gem formed within the soft tissue of a living shelled mollusk. |
| Variscite | 3.5–4.5 | Indistinct | Orthorhombic | A hydrated aluminum phosphate mineral prized as a green ornamental stone. Often confused… |
| Chrysocolla | 2–4 | None | Orthorhombic | A hydrated copper silicate. The ranges in this entry are the mineral's: hardness 2–4, SG… |
| Coral | 3–4 | None | Aggregate | An organic gemstone formed from the skeletal remains of marine polyps. |
| Cuprite | 3.5–4 | Indistinct | Cubic | A copper oxide mineral known for its intense red color, but is too soft for most jewelry… |
| Fluorite | 4 | Perfect | Cubic | Known for its perfect cleavage in four directions and often strong fluorescence. |
| Jet | 2.5–4 | None | Amorphous | Organic gemstone formed from compacted driftwood (Araucaria trees) buried and transformed… |
| Malachite | 3.5–4 | Perfect | Monoclinic | A green copper carbonate hydroxide mineral, known for its distinctive banded appearance. |
| Rhodochrosite | 3.5–4 | Perfect | Trigonal | Manganese carbonate with intense rose-red to pink color and extreme birefringence. Best… |
| Sphalerite | 3.5–4 | Perfect | Cubic | A zinc sulfide mineral with dispersion more than three times that of diamond, but is too… |
| Howlite | 3.5 | None | Monoclinic | White to gray calcium borosilicate hydroxide with gray-black veining. Widely dyed blue or… |
| Calcite | 3 | Perfect | Trigonal | Calcite is the classic demonstration of double refraction. A clear rhomb — the variety… |
| Ivory | 2.5–3 | None | Aggregate | Ivory is dentine from the tusks of elephants, mammoths, walrus, hippopotamus, and other… |
| Amber | 2–2.5 | None | Amorphous | Fossilized tree resin; low density and organic inclusions distinguish it from glass and… |
| Cinnabar | 2–2.5 | Perfect | Trigonal | A toxic mercury sulfide mineral with a bright scarlet to brick-red color, rarely used as… |
Click a column header to re-sort the table.
Which gemstone is the hardest on the Mohs scale?
Diamond is the hardest gem in this reference at Mohs 10. Nothing else in the chart reaches 10; the next hardest is Moissanite at 9.25.
Which gemstones have a Mohs hardness of 7?
50 of the 132 species in this chart have a hardness range that includes 7, including Agate, Almandine Garnet, Amethyst, Ametrine, Andalusite, Aventurine, Bloodstone, Carnelian, Cassiterite, Chalcedony, and 40 more. Because so many species overlap at 7, hardness alone cannot separate them — combine it with refractive index and specific gravity.
What are the softest gemstones?
The softest materials in this chart are Amber (2–2.5), Chrysocolla (2–4), Cinnabar (2–2.5), Ivory (2.5–3), Jet (2.5–4). Stones below Mohs 7 are vulnerable to scratching by everyday dust (which contains quartz) and need protective settings or occasional-wear use.
All instrument charts: Refractive Index · Specific Gravity · Birefringence · Fluorescence · Pleochroism · Spectroscope · Optic Character · Chelsea & Hanneman Filters · Dispersion · Magnetism
See also: Full Reference Database · How to Identify a Gemstone · Exam Study Guides · Open dataset (CSV & JSON, CC BY 4.0)
Use hardness as a supporting test in Loupewise — combined with RI and SG it confirms your identification.
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