Mineral gems survive centuries of wear. Organic gems — the ones made by living things — do not, unless they are treated with a care that most jewellery does not need. Pearl, coral, amber, jet, shell and bone are all soft (hardness 2–4.5 on the Mohs scale), all porous or chemically reactive, and all damaged by things a sapphire would not notice. Understanding why makes the care rules obvious.
Why they are vulnerable
Softness. Household dust contains quartz at hardness 7. Anything below 7 will be scratched by it over time; at 2.5–4, organic gems scratch visibly within months of careless wear and storage.
Chemistry. Pearl, coral and shell are calcium carbonate, which dissolves in acid — including the mild acids in sweat, perfume, hairspray, cosmetics, fruit juice and vinegar. Amber and jet are organic polymers that soften in solvents, craze in heat and oxidise in light.
Porosity. Coral and untreated turquoise absorb oils and dyes; pearls absorb cosmetics; bone takes stains.
Structure. Pearl nacre is layers that can delaminate; a thin-nacre cultured pearl can wear through to its bead. Coral has grain and can split along it. Amber can craze.
The rules
Last on, first off. Put jewellery on after perfume, cosmetics and hairspray have dried; take it off before washing, swimming, exercising or sleeping.
Wipe after wear. A soft, dry or barely damp cloth removes sweat and oils before they act.
No ultrasonic, no steam, no chemicals. Ultrasonic cleaners crack pearls and loosen coral; steam damages both; jewellery cleaners are usually acidic or solvent-based. Clean with a soft cloth and, if needed, a little mild soap in lukewarm water, dried immediately. Never soak pearls — the silk thread weakens and the nacre can be affected.
Store separately. In a soft pouch or a lined compartment, away from harder gems and metal. Not in an airtight plastic bag for long periods — pearls in particular need some humidity or they can dry and crack.
Re-string pearls regularly. Silk thread stretches and frays; a strand worn often should be re-strung every year or two, knotted between pearls so that a break loses one, not all. Re-stringing a mala covers the same principles for beads.
Avoid heat and light. Amber and jet in a sunny window will craze and fade; pearls dry out near radiators.
Rings are the hardest wear. Organic gems in rings take knocks and scrapes daily. Pendants, earrings and brooches are safer settings.
What damage looks like
- Pearls: dull, chalky patches where nacre has eroded; exposed bead at the drill hole; a "wearing through" spot; cracked or peeling nacre; yellowing from cosmetics.
- Coral: dulled polish; white spots where acid has etched; splits along the grain.
- Amber: surface crazing (a network of fine cracks); darkening; stickiness after solvent contact.
- Jet: scratches; loss of polish.
- Shell and bone: scratches; staining; cracking along layers.
What a laboratory can say about condition
A report can note nacre thickness (by X-ray), surface erosion, cracks, repairs, coatings and previous treatments, and can identify whether damage is to the gem or to a coating. It cannot reverse damage. Some can be improved by repolishing (coral, amber, jet) at the cost of material; pearls cannot be repolished.
Frequently asked questions
Can pearls be worn every day?
Yes, with the rules above, and they benefit from wear — skin moisture keeps them from drying. Daily wear needs annual re-stringing and careful storage.
Is it safe to use a jewellery cleaning solution on coral?
No. Most are acidic or contain ammonia. Use a soft cloth and mild soap only.
Why did my amber go cloudy?
Solvent contact (perfume, alcohol, nail polish remover) or crazing from heat and light. Cloudiness from solvent may be permanent.
Can a thin-nacre pearl be repaired?
No. Once the nacre wears through to the bead there is no remedy. This is why nacre thickness on the report matters.
Do treated organic gems need the same care?
Stabilised and coated pieces are somewhat more robust, but the rules still apply — coatings scratch and solvents attack them.