Gem Care and Durability

Gemstone stability, cleaning methods, setting recommendations, storage guidelines, and jewellery suitability for different gem species.

By Fabian Moor Last updated
durability care cleaning stability settings jewellery

Introduction

Gemstone durability is the practical measure of how well a gem withstands everyday
wear, cleaning, and storage. It encompasses three distinct factors (hardness,
toughness, and stability), and a gem suited to daily ring wear must score adequately
on all three. Hardness alone is insufficient: tanzanite reaches Mohs 6.5 yet its
perfect cleavage on {010} makes it highly vulnerable during setting, while jade at
Mohs 6–7 is among the toughest gem materials owing to its interlocking fibrous
microstructure. Chemical and thermal stability add a further dimension: opal contains
3–21 % water and can craze irreversibly on dehydration; pearls at Mohs 2.5–4.5
dissolve in mild acid; and the fracture-filling resin present in most emeralds
exudes under the heat of a jeweller's torch. Matching the correct cleaning method
and setting type to each species is therefore a core professional competency, not an
afterthought. [1]

The Three Durability Factors

Hardness

  • Resistance to scratching
  • Measured on Mohs scale (1-10)
  • Important for wear resistance
  • Gems below 7 scratch easily
  • Dust contains quartz (H 7)

Toughness

  • Resistance to breaking/chipping
  • Related to crystal structure
  • Cleavage reduces toughness
  • Jade is tougher than diamond
  • Important for impact resistance

Stability

  • Resistance to chemicals/light/heat
  • Fading from light exposure
  • Damage from heat or acids
  • Some gems are temperature sensitive
  • Important for long-term care

Hardness Considerations

The Mohs scale is ordinal, not linear – the jump from 9 to 10 is enormous. Household
dust contains quartz particles (H 7), so gems below 7 will gradually accumulate
scratches during normal wear. [1]

Hardness Categories for Jewellery
Category Hardness Suitability Examples
Excellent 8-10 Daily ring wear Diamond, ruby, sapphire, chrysoberyl
Good 7-7.5 Everyday with care Quartz, tourmaline, garnet, beryl
Fair 6-7 Occasional wear; protective settings Peridot, tanzanite, moonstone
Poor 5-6 Earrings/pendants; very careful ring Opal, turquoise, apatite
Fragile <5 Display or very protected wear Pearl, coral, amber, fluorite

Toughness and Cleavage

Cleavage – the tendency to break along crystallographic planes – significantly affects
toughness. Even hard gems can be brittle.

High-Risk Cleavage Gems

Gem Cleavage Risk
Diamond Perfect octahedral {111} Can cleave with sharp blow
Topaz Perfect basal {001} Very prone to chipping
Kunzite Perfect prismatic Extremely fragile for setting
Fluorite Perfect octahedral {111} Very brittle
Tanzanite Perfect {010} Easily damaged in setting
Feldspar (moonstone) Perfect two directions Prone to chipping

Tough Gems

Some gems have exceptional toughness despite moderate hardness:

  • Nephrite jade (H 6-6.5): Interlocking fibrous structure
  • Jadeite (H 6.5-7): Granular interlocking structure [2]
  • Chalcedony (H 7): Microcrystalline aggregate

These gems resist chipping better than single-crystal gems of higher hardness.

Stability Factors

Many gems are sensitive to environmental conditions that can cause fading,
colour change, or physical damage.

Light Sensitivity

Gem Risk Notes
Kunzite High Fades significantly; store in dark [3]
Amethyst Moderate Can fade with prolonged exposure [4]
Rose quartz Low to moderate May fade slightly
Brown topaz High Natural brown fades; irradiated stable
Chrysoprase Moderate Can fade and dry out
Turquoise Moderate Can fade and dehydrate

Heat Sensitivity

Gem Risk Damage Type
Opal Very high Crazing from dehydration
Pearl High Nacre damage, peeling
Emerald (oiled) High Oil can exude
Tanzanite High Colour may change; cleavage risk
Tourmaline Moderate Some colours may change
Kunzite High Can lose colour

Chemical Sensitivity

Gem Sensitive To Effect
Pearl Acids, perfume, hairspray Nacre dissolution
Coral Acids Surface etching
Turquoise Oils, cosmetics Discolouration
Malachite Acids Surface damage
Lapis lazuli Acids Pyrite tarnish, surface damage
Amber Solvents, alcohol Surface damage

Cleaning Methods

Different gems require different cleaning approaches. Using the wrong method can
cause permanent damage.

Safe Cleaning Methods

Method Description Safe For Never Use For
Warm soapy water Mild dish soap, soft brush Most gems Porous gems (turquoise)
Ultrasonic Sound waves agitate cleaning solution Diamond, ruby, sapphire (untreated) Emerald, tanzanite, opal, pearl
Steam High-pressure steam jet Diamond, ruby, sapphire (untreated) Filled gems, porous gems, soft gems
Dry brush Soft brush, no liquid Porous gems N/A (gentle method)

Ultrasonic Cleaning Safety

Ultrasonic cleaners use high-frequency sound waves to agitate a cleaning solution,
but this same cavitation energy can cause damage to: [5]

  • Filled gems: Can remove or damage fillers (emerald, ruby) [6]
  • Gems with cleavage: Vibration can propagate fractures
  • Fragile inclusions: Can cause expansion/damage
  • Organic gems: Can damage pearl nacre, amber
  • Treated gems: May affect surface treatments

Steam Cleaning Safety

Steam cleaning combines heat and moisture, dangerous for:

  • Oiled emeralds: Heat can remove oil [6]
  • Heat-sensitive gems: Thermal shock risk
  • Filled gems: Heat damages many fillers
  • Opal: Rapid temperature change causes crazing

Cleaning Safety Chart

Cleaning Method Safety by Gem
Gem Warm Soapy Water Ultrasonic Steam
Diamond (natural) Safe Usually safe Usually safe
Ruby/Sapphire (untreated) Safe Usually safe Usually safe
Ruby/Sapphire (heated) Safe Caution Caution
Emerald (oiled) Safe Never Never
Aquamarine Safe Usually safe Usually safe
Tanzanite Safe Never Never
Tourmaline Safe Caution Caution
Opal Caution Never Never
Pearl Safe (brief) Never Never
Turquoise Never (dry brush) Never Never

Setting Recommendations

The choice of setting can protect vulnerable gems or expose durable gems to show
their beauty.

Protective Settings

Setting Type Protection Level Best For
Bezel High Soft gems, cleavage-prone gems
Half-bezel Moderate Balance of protection and light
Flush/gypsy Very high Rings for active wearers
Halo Moderate Central stone protected by smaller stones

Exposed Settings

Setting Type Protection Level Requires
Prong/claw Low Hardness 7+ for rings
Tension Low Very hard, tough gems only
Bar Low to moderate Harder gems preferred

Setting by Gem Type

Recommended for prong settings (rings):
Diamond, ruby, sapphire, chrysoberyl, spinel

Recommend bezel or protective settings:
Emerald, tanzanite, opal, moonstone, tourmaline, peridot

Best avoided in rings:
Kunzite, fluorite, apatite, pearl (unless protective setting)

Storage Guidelines

Separation

Store gems separately to prevent harder gems from scratching softer ones:

  • Individual pouches or compartments
  • Soft fabric lining
  • Never loose in a box together
  • Diamond will scratch everything else

Environment

  • Humidity: Some gems need moisture (opal, pearl); others need dry (iron pyrite)
  • Light: Store light-sensitive gems in dark containers
  • Temperature: Avoid extreme temperatures; room temperature ideal
  • Air: Some gems need ventilation; airtight can trap moisture

Special Storage Needs

Gem Special Requirements
Opal Damp cotton nearby; avoid airtight; stable temperature
Pearl Breathable container; occasional wear maintains moisture
Amber Away from solvents and heat
Kunzite Complete darkness
Turquoise Away from oils and cosmetics

Jewellery Suitability Chart

Gem Suitability by Jewellery Type
Gem Daily Ring Occasional Ring Earrings Pendant Bracelet
Diamond Excellent Excellent Excellent Excellent Excellent
Ruby/Sapphire Excellent Excellent Excellent Excellent Excellent
Emerald Caution Good Excellent Excellent Caution
Aquamarine Good Excellent Excellent Excellent Good
Tanzanite Poor Caution Good Good Poor
Tourmaline Good Excellent Excellent Excellent Good
Opal Poor Caution Good Good Poor
Pearl Caution Good Excellent Excellent Caution
Moonstone Caution Good Excellent Excellent Caution
Peridot Caution Good Good Good Caution
Kunzite Poor Poor Good Good Poor
Topaz Good Excellent Excellent Excellent Good

Special Care Gems

Opal

Opal contains 3-21% water and is prone to "crazing" (network of fine cracks) [7][8]:

  • Avoid rapid temperature changes
  • Store with damp cotton (not wet)
  • Never use ultrasonic or steam
  • Keep away from direct sunlight and heat
  • Doublets and triplets are especially vulnerable to water

Pearl

Pearls are sensitive to acids, cosmetics, and drying:

  • Apply perfume and hairspray before putting on pearls
  • Wipe with soft cloth after wearing
  • Store in breathable fabric, not plastic
  • Restring regularly (silk stretches and weakens)
  • Occasional wearing maintains moisture balance

Emerald

Nearly all emeralds are oiled to improve apparent clarity [6][9]:

  • Oil can dry out or exude over time
  • Avoid ultrasonic and steam cleaning
  • Avoid heat (jeweller's torch is dangerous)
  • May need periodic re-oiling [10]
  • Store away from heat sources

Tanzanite

Tanzanite has perfect cleavage and is heat-sensitive [11]:

  • Extremely vulnerable during setting (cleavage)
  • Never use ultrasonic or steam
  • Avoid sudden temperature changes
  • Not recommended for daily ring wear
  • Excellent for earrings and pendants

Care Summary

References

  1. ↑ 1. Read, P. (2012). Gemmology (3rd ed.). Butterworth-Heinemann. ISBN: 9780750664493. DOI: 10.4324/9780080507224.
  2. ↑ 2. Reller, A.; Wilde, W.; Wiedemann, H. (1993). Thermal reactivity of jadeite and nephrite. Journal of Thermal Analysis, 40. DOI: 10.1007/bf02546559.
  3. ↑ 3. Nassau, K.; Valente, G. (1987). The Seven Types of Yellow Sapphire and their Stability to Light. Gems & Gemology, 23(4), 222–231. DOI: 10.5741/gems.23.4.222.
  4. ↑ 4. Nassau, K. (1981). Artificially Induced Color in Amethyst-Citrine Quartz. Gems & Gemology, 17(1), 37–44. DOI: 10.5741/gems.17.1.37.
  5. ↑ 5. Mason, T. (1999). Sonochemistry. Oxford University Press. DOI: 10.1093/hesc/9780198503712.003.0002.
  6. ↑ 6. Kammerling, R.; Koivula, J.; Kane, R.; Maddison, E.; Shigley, J.; Fritsch, E. (1991). Fracture Filling of Emeralds: Opticon and Traditional "Oils". Gems & Gemology, 27(2), 70–85. DOI: 10.5741/gems.27.2.70.
  7. ↑ 7. Banerjee, A.; Wenzel, T. (1999). Black opal from Honduras. European Journal of Mineralogy, 11(2), 401–408. DOI: 10.1127/ejm/11/2/0401.
  8. ↑ 8. Herrmann, J. (2022). On the Origin of 'Crazing' (Cracking) in Opal. SSRN Electronic Journal. DOI: 10.2139/ssrn.4241788.
  9. ↑ 9. Nassau, K. (1994). More on the antiquity of emerald oiling. The Journal of Gemmology, 24(2), 109–115. DOI: 10.15506/jog.1994.24.2.109.
  10. ↑ 10. Johnson, M.; Elen, S.; Muhlmeister, S. (1999). On the Identification of Various Emerald Filling Substances. Gems & Gemology, 35(2), 82–107. DOI: 10.5741/gems.35.2.82.
  11. ↑ 11. Newton, R. (1965). The Thermal Stability of Zoisite. The Journal of Geology, 73(3). DOI: 10.1086/627075.

Related Topics

Physical PropertiesGemstone TreatmentsGrading and Valuation