Gemstone Care
A gemstone that survived millions of years underground is generally very durable. However, it can still be dulled by a dust cloth, clouded by perfume or cracked by a sudden change in temperature. Good care is mostly a matter of knowing which risks apply to which gemstone.
Below, each gem carries its hardness, toughness, vulnerabilities and safe cleaning methods.
Durability
Three Things That Determine How a Gem Wears
01
Hardness
Resistance to scratching, measured on the Mohs scale from 1 to 10. Household dust contains quartz, at 7, so softer gems slowly lose their polish.
02
Toughness
Resistance to chipping and breaking. It is not the same as hardness: diamond is the hardest gem yet can cleave from a sharp blow, while jade is softer but exceptionally tough.
03
Stability
Resistance to heat, light, humidity and chemicals. Some gems fade in sunlight; others are etched by substances as ordinary as perfume or perspiration.
Pearl2.5Coral3–4Lapis5–6Moonstone6–6.5Quartz7Aquamarine7.5–8Sapphire9Diamond10
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Everyday Habits
Four Rules That Protect Every Gem
Last on, first off
Put jewelry on after perfume, hairspray and lotion — and take it off before swimming, cleaning or the gym.
Store stones apart
Harder gems scratch softer ones. Give each piece its own pouch or compartment — or keep a loose stone in its numbered Otzera case.
Warm, soapy water
Mild soap, warm water and a soft brush are safe for every gem on this page. Rinse well and dry with a soft cloth.
Mind heat and machines
Sudden temperature changes can fracture many gems, and ultrasonic and steam cleaners are unsafe for most. Check a stone’s entry before using either.
The Gem Guide
Durability and Care, A to Z
Open any gem for its care notes. Opening another closes the first.
Everyday Wear
Hard, tough and stable. Suited to rings worn daily.
Wear with Care
Durable in any jewelry with sensible precautions.
Protective Settings
Cleavage or low toughness. Favor pendants, earrings or guarded mounts.
Special Care
Soft, porous or chemically sensitive. Clean by hand only.
✓Safe◐Usually safe — not for fracture-filled, dyed or included stones✕Avoid
AChrysoberylAlexandriteMohs 8.5Everyday Wear
ToughnessExcellent
Watch forStable to heat, light and common chemicals. No cleavage.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam◐Usually safe
Treatment & notesUsually untreated. Fracture-filled stones take warm soapy water only.
Source: GIA Alexandrite Care Guide
AOrganicAmberMohs 2–2.5Special Care
ToughnessPoor
Watch forBurns at low temperatures, darkens with prolonged light and is damaged by chemicals.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesDyes used to color amber can fade or change.
Source: GIA Amber Care Guide
QuartzAmethystMohs 7Wear with Care
ToughnessGood
Watch forSudden temperature changes can fracture it; color can fade in prolonged intense light. Ordinary dust contains quartz and will scratch it over time.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam✕Avoid
Treatment & notesRarely dyed or fracture-filled — those stones take warm soapy water only.
Source: GIA Amethyst Care Guide
AQuartzAmetrineMohs 7Wear with Care
ToughnessGood
Watch forAbrupt temperature changes can fracture it; color can fade in prolonged intense light.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam✕Avoid
Treatment & notesRarely dyed or fracture-filled — those stones take warm soapy water only.
Source: GIA Ametrine Care Guide
APhosphateApatiteMohs 5Special Care
ToughnessPoor
Watch forSoft enough to scratch in daily wear and prone to fracturing under sudden temperature change.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesBest suited to pendants, earrings and the collection case.
BerylAquamarineMohs 7.5–8Wear with Care
ToughnessGood
Watch forKeep away from heat. Color is stable in light; only hydrofluoric acid attacks it.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam◐Usually safe
Treatment & notesOccasionally fracture-filled. Skip ultrasonic and steam for filled stones or those with fractures or liquid inclusions.
Source: GIA Aquamarine Care Guide
BBarium titanium silicateBenitoiteMohs 6–6.5Wear with Care
ToughnessFair — brittle
Watch forSofter than quartz, so it abrades more easily than sapphire. Sensitive to rapid temperature change and ultrasonic vibration; attacked by hydrofluoric acid.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesAlmost always untreated. Found in gem quality almost exclusively in San Benito County, California.
CAgate · Onyx · CarnelianChalcedonyMohs 6.5–7Wear with Care
ToughnessGood
Watch forDyed material can lose color to solvents such as acetone or alcohol and to prolonged sunlight.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam✕Avoid
Treatment & notesFrequently dyed; bleached material is more brittle and absorbent.
Including Cat’s-EyeChrysoberylMohs 8.5Everyday Wear
ToughnessExcellent
Watch forStable to heat, light and common chemicals. The same species as alexandrite.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam◐Usually safe
Treatment & notesUsually untreated. Fracture-filled stones take warm soapy water only.
QuartzCitrineMohs 7Wear with Care
ToughnessGood
Watch forAbrupt temperature changes can fracture it; color may fade with prolonged exposure to intense light.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam✕Avoid
Treatment & notesRarely dyed or fracture-filled — those stones take warm soapy water only.
Source: GIA Citrine Care Guide
COrganicCoralMohs 3–4Special Care
ToughnessFair
Watch forCosmetics, perfume, chlorinated pools and heat can strip its polish and color.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesOften dyed, bleached, waxed or plastic-stabilized. Wipe with a soft cloth; never soak.
Source: GIA: Coral Care
DCarbonDiamondMohs 10Everyday Wear
ToughnessGood — but cleaves
Watch forUnaffected by chemicals and acids, but a hard blow along its cleavage can chip it. Sudden, extreme temperature change is the real threat.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam◐Usually safe
Treatment & notesGIA advises against ultrasonic and steam cleaners at home — they can loosen stones in their settings. Fracture-filled diamonds need gentle cleaning only.
Source: GIA Diamond Care Guide
BerylEmeraldMohs 7.5–8Wear with Care
ToughnessFair to good
Watch forHeat can extend fractures. The oils and resins in its fractures can deteriorate with heat, light and chemicals — even hot water.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesAround 90% of emeralds are fracture-filled with oil, resin or polymer.
Source: GIA Emerald Care Guide · Read our Emerald guide
FAmazonite · Orthoclase · AndesineFeldsparMohs 6–6.5Protective Settings
ToughnessPoor
Watch forTwo directions of cleavage — a hard blow can break it. Feldspars are attacked by hydrochloric acid, so avoid heat and bleach-based cleaners.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesSome red andesine is diffusion-treated for color, and amazonite may be impregnated. Moonstone, sunstone and labradorite are feldspars too — see their entries.
Including Tsavorite & DemantoidGarnetMohs 6.5–7.5Wear with Care
ToughnessFair to good
Watch forStable to light and chemicals; only hydrofluoric acid attacks it. Demantoid is the softest of the family.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam✕Avoid
Treatment & notesFracture filling is rare. Skip ultrasonic for fractured stones.
Source: GIA Garnet Care Guide
HeliodorGolden BerylMohs 7.5–8Wear with Care
ToughnessGood
Watch forKeep away from heat; attacked by hydrofluoric acid. Irradiated beryl color can fade in bright light.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam◐Usually safe
Treatment & notesSkip ultrasonic and steam for stones with fractures or liquid inclusions.
Grossular garnetHessoniteMohs 6.5–7.5Wear with Care
ToughnessFair to good
Watch forStable to light and chemicals; only hydrofluoric acid attacks it. Protect it from hard knocks.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam✕Avoid
Treatment & notesUsually untreated. Skip ultrasonic for fractured or heavily included stones.
Source: GIA Garnet Care Guide
ICordieriteIoliteMohs 7–7.5Protective Settings
ToughnessFair to poor
Watch forPerfect cleavage in one direction — a hard blow can split it. High heat or sudden temperature change can break it.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesNot typically treated. Best in protective settings or pendants.
Source: GIA Iolite Care Guide
JJadeite & NephriteJadeMohs 6–7Everyday Wear
ToughnessExceptional
Watch forTough rather than hard: very resistant to breaking, but it can scratch. A jeweler’s torch and warm acids can harm it.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam◐Usually safe
Treatment & notesOften dyed, bleached, impregnated or coated — treated jade takes warm soapy water only.
Source: GIA Jade Care Guide
SpodumeneKunziteMohs 6.5–7Protective Settings
ToughnessPoor
Watch forPerfect cleavage in two directions. Color can fade with prolonged heat or intense light — an evening stone.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesMay be irradiated and heated; treated or not, it can fade the same way.
Source: GIA Kunzite Care Guide
LFeldsparLabradoriteMohs 6–6.5Protective Settings
ToughnessPoor
Watch forCleavage in two directions. Feldspars are rapidly attacked by hydrochloric acid — avoid bleach-based cleaners.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesSome feldspar is diffusion-treated for color, a permanent treatment.
LRockLapis LazuliMohs 5–6Special Care
ToughnessFair
Watch forHeat and solvents can strip wax sealers; dye can rub off with acetone or denatured alcohol.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesOften dyed and waxed or oiled. Test any cleaning on a hidden area first.
Source: GIA Lapis Lazuli Care Guide
MCopper carbonateMalachiteMohs 3.5–4Special Care
ToughnessPoor
Watch forVery soft, and vulnerable to chlorine, ammonia, perfume and oils.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesStore apart from harder stones and wipe clean with a soft cloth.
MFeldsparMoonstoneMohs 6–6.5Protective Settings
ToughnessPoor
Watch forTwo directions of cleavage — a hard blow can break it. High heat or sudden temperature change can fracture it.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesBest in pendants, earrings and pins rather than rings.
Source: GIA Moonstone Care Guide
BerylMorganiteMohs 7.5–8Wear with Care
ToughnessGood
Watch forColor is stable in light. Keep away from heat; attacked by hydrofluoric acid.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam◐Usually safe
Treatment & notesRarely fracture-filled. Skip ultrasonic and steam for filled or fractured stones.
Source: GIA Morganite Care Guide
NJadeNephriteMohs 6–6.5Everyday Wear
ToughnessExceptional
Watch forAmong the toughest of all gem materials — very resistant to breaking, though it can scratch. A jeweler’s torch and warm acids can harm it.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam◐Usually safe
Treatment & notesSometimes dyed or impregnated — treated nephrite takes warm soapy water only.
Hydrated silicaOpalMohs 5–6.5Special Care
ToughnessVery poor to fair
Watch forHeat, intense light and sudden temperature change can craze or crack it; caustic alkaline solutions attack it.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesMay be impregnated with oil, wax or plastic, or sugar- and smoke-treated.
Source: GIA Opal Care Guide
POrganicPearlMohs 2.5Special Care
ToughnessGood, lessens with age
Watch forDamaged by all acids and many chemicals — hairspray, perfume, cosmetics, even perspiration. Last on, first off.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesMay be dyed, coated or impregnated. Wipe with a soft cloth after each wearing; let strands dry fully before wearing.
Source: GIA Pearl Care Guide
POlivinePeridotMohs 6.5–7Wear with Care
ToughnessFair to good
Watch forRapid or uneven heat can fracture it. Attacked by sulfuric and hydrochloric acid, and slowly by acidic perspiration.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesWarm soapy water is the best method.
Source: GIA Peridot Care Guide
RCarbonateRhodochrositeMohs 3.5–4Special Care
ToughnessPoor — fragile
Watch forPerfect cleavage in three directions and sensitive to heat.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesMay be impregnated. Soak in room-temperature soapy water, rinse lightly and dry with a very soft cloth.
QuartzRose QuartzMohs 7Wear with Care
ToughnessGood
Watch forGenerally stable to light and heat.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesOccasionally irradiated to intensify its color.
Source: GIA Rose Quartz Care Guide
CorundumRubyMohs 9Everyday Wear
ToughnessExcellent
Watch forStable to heat, light and common chemicals — though boric acid powder etches it, and mild acids like lemon juice harm treated stones.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam◐Usually safe
Treatment & notesUntreated, heated or diffused: ultrasonic and steam are usually safe. Glass-filled, cavity-filled or dyed: damp cloth only.
Source: GIA Ruby Care Guide · Read our Ruby guide
CorundumSapphireMohs 9Everyday Wear
ToughnessExcellent
Watch forStable to heat, light and common chemicals — though boric acid powder etches it, and mild acids harm fracture-filled or dyed stones.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam◐Usually safe
Treatment & notesUntreated, heated or diffused: ultrasonic and steam are usually safe. Fracture-filled or dyed: damp cloth only.
SpinelSpinelMohs 8Everyday Wear
ToughnessGood
Watch forHigh heat can fade some colors; stable to light and chemicals.
Cleaning
Warm soapy water✓Safe
Ultrasonic◐Usually safe
Steam◐Usually safe
Treatment & notesHeat treatment is stable. Rare fracture-filled stones take soapy water or a damp cloth only.
Source: GIA Spinel Care Guide
FeldsparSunstoneMohs 6.5–7.2Protective Settings
ToughnessPoor
Watch forCleavage in two directions. Avoid heat and bleach-based cleaners — feldspars are attacked by hydrochloric acid.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesRarely fracture-filled. Best in pendants, earrings and pins.
Source: GIA Sunstone Care Guide
ZoisiteTanzaniteMohs 6–7Wear with Care
ToughnessFair
Watch forHas cleavage, so avoid hard knocks. Keep away from sudden temperature change and hydrochloric or hydrofluoric acid.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesHeat treatment is stable. Rare coatings are not permanent and can scratch.
Source: GIA Tanzanite Care Guide
TopazTopazMohs 8Wear with Care
ToughnessFair
Watch forHas cleavage, so avoid hard knocks and sudden temperature change. Some yellow-to-brown colors can fade in sunlight.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesCoated topaz: no abrasive cleaners or buffing wheels.
Source: GIA Topaz Care Guide
Including ParaíbaTourmalineMohs 7–7.5Wear with Care
ToughnessFair
Watch forHigh heat can alter color and thermal shock can fracture it. Unaffected by chemicals.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesOften heated or irradiated; irradiated color can fade with heat or bright light.
TPhosphateTurquoiseMohs 5–6Special Care
ToughnessFair to good
Watch forDiscolored by chemicals, cosmetics, skin oils and perspiration; high heat damages its surface.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesOften surface-treated or impregnated — keep heat and solvents away.
Source: GIA Turquoise Care Guide
ZirconZirconMohs 6–7.5Wear with Care
ToughnessFair to good
Watch forBrittle — facet edges can chip. Heat can alter color, and heated blue or colorless stones may revert in prolonged bright light.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesBlue and colorless zircon are commonly heat-treated.
Source: GIA Zircon Care Guide
Green Zoisite · Thulite · AnyoliteZoisiteMohs 6–7Wear with Care
ToughnessFair
Watch forThe species that includes tanzanite. Has cleavage, so avoid hard knocks and sudden temperature change.
Cleaning
Warm soapy water✓Safe
Ultrasonic✕Avoid
Steam✕Avoid
Treatment & notesWarm soapy water only.
A Note on Care
When in Doubt, Ask
The sources for each gem are linked in its care notes. This is general guidance, not a substitute for a jeweler’s inspection of a specific piece — treated stones, fracture-filled stones and older jewelry may need more caution than shown here.
Every Otzera gemstone arrives in its own numbered case, which is also the safest place to keep a loose stone. If you are unsure how to care for a stone you own, write to us at hello@otzera.com.