The Systematic Maintenance of Pearl Jewellery

Totapari Knowledge Series · Pearls

Why Pearls Need Different Care

Pearls are unlike most gemstones because they are organic, formed inside a living mollusc. Everything about how they must be looked after follows from that one fact.

• An organic bio-composite — unlike inorganic gemstones formed by geological pressure, pearls are made by living creatures. They are calcium carbonate in the form of aragonite, bound by conchiolin, a fibrous protein, together with a small amount of water.
• The vulnerability of nacre — nacre's strength comes from a brick-and-mortar construction at the nanoscale. Aragonite occurs as hexagonal platelets only a few hundred nanometres thick, stacked in a dense, ordered arrangement and bonded by conchiolin, which acts as the mortar.

  Lustre and orient both come from light reflecting off those microscopic platelets. But because they are held by an organic protein, the surface is porous and reacts to chemicals, to temperature cycling and to drying out.

  Think of it as a chalky or bony substance. Anything of that kind is damaged by moisture and by chemicals — and a pearl is damaged by the absence of moisture too. It needs to be kept somewhere with adequate humidity and no chemicals in the air.

• Hardness disparity — at only 2.5 to 4.5 on the Mohs scale, pearls are softer than the quartz in household dust, which is 7.0, and far softer than sapphire or diamond. They scratch immediately and abrade easily.

The precautions below protect the pearl and make it last. For the vocabulary behind them, see our pearl glossary, and for why different pearls differ in durability, our guide to pearl types.

• Last on, first off — the single rule that matters most. It keeps pearls away from the solvents in modern beauty products.
• How the damage happens — ethanol and other volatile solvents in perfume do not simply sit on the surface. They dissolve the conchiolin matrix, leaving microscopic pitting and a flat, chalky appearance that cannot be undone without risky repolishing.
• The thirty-minute rule — apply makeup, hairspray and perfume at least half an hour before putting pearls on, so the volatile compounds have fully evaporated from the skin.

• After every wear — wipe with a clean, lint-free microfibre or soft cotton cloth. Microfibre is better, because its fine fibres lift skin oils and acids before they can etch the nacre.
• Occasional wet cleaning — for heavier soiling, use lukewarm distilled water with one drop of pH-neutral, non-detergent soap: a baby shampoo, or the unscented soap you use on your face.
  • Method — dampen the cloth, wring it until nearly dry, and wipe each pearl individually.
  • Knots — lift grime from between the pearls with a barely damp cotton bud, taking care not to fray the thread.
• Drying matters as much as washing — lay the strand flat on a dry towel and leave it several hours, or overnight, before storing. Moisture trapped in the drill holes or in the silk will stretch the thread, rot it, or draw dirt inside.

• Chemical erosion — acids and surfactants in sunscreens, lotions and detergents erode the nacre, causing irreversible yellowing or darkening.
• Dehydration — pearls hold a natural moisture content of two to four per cent, essential to their structure. Dry environments — a bank locker, a shelf near a heating vent — make the nacre craze, crack finely, and turn brittle.
• Perspiration — sweat is acidic. Left unwiped, it crystallises in the pores of the nacre, causing micro-abrasion and a foggy film across the surface.
• Contact with metal beads — where pearls are strung with gold beads, the wider drill holes in the metal let the beads ride over the knots and rub directly against the nacre. The result is black staining, from the alloy metals and from the abrasion itself.

• Keep each piece apart — store every piece in its own breathable fabric pouch of silk, cotton or velvet, away from harder jewellery that will scratch the nacre.
• Manage the humidity
  • In dry climates — keep a barely damp cotton ball, or a small open glass of water, near the storage area. Never in contact with the pearls.
  • Unfinished wood helps — a cedar box acts as a natural regulator, absorbing and releasing moisture as the air changes.
• Never airtight — plastic bags and sealed containers trap dry air and stop the pearls breathing, which accelerates the very dehydration you are trying to prevent.

• Strung necklaces and bracelets — always store flat. Hanging them on a stand lets gravity stretch the silk or nylon, opening gaps between the pearls.
• Rings and earrings — these are usually half-drilled and held with a specialised jewellery adhesive.
  • The glue is the weak point — hot water, steam and solvents dissolve it, and the pearl falls out.
  • Rings take the most punishment — remove them before any manual work, and before washing your hands.
• Durability differs by type — Akoya pearls carry thin nacre, roughly 0.35 to 0.7 mm, and can blink, showing the shell nucleus through a worn surface. South Sea pearls, at 2 to 6 mm of nacre, and freshwater pearls, which are often solid nacre throughout, stand up to long wear far better.

• Carry-on only — aircraft holds swing through extreme temperatures at very low humidity, which can crack a pearl. Never check them in.
• Packing — thread a necklace through a drinking straw, or roll it in a microfibre cloth, to stop tangling and friction.
• In hotels — keep pearls off the bathroom counter, where they meet the aerosolised toiletries of every previous guest.

• How often — a strand worn weekly should be restrung every one to two years. Occasional pieces may go three to five.
• Signs the thread is failing
  • Fraying — the silk looks shredded or woolly where it enters the drill holes.
  • Stretching — visible gaps between pearls and knots, or the necklace hanging longer than it used to.
  • Knots disappearing — a knot has compressed enough to slip inside a drill hole.
• Why knotting matters — a proper restring puts a knot between every pearl. It stops them rubbing against each other, and it means that if the strand breaks you lose one pearl rather than all of them.

A pearl looked after well outlives the person who bought it.

Frequently Asked Questions