Why Pearls Lose Their Lustre

A pearl's glow comes from layers of nacre — thin, overlapping plates of aragonite bound together with a protein called conchiolin. It is beautiful but delicate. On the Mohs scale, pearls sit somewhere between 2.5 and 4.5, far softer than most gemstones. Almost everything they meet leaves a mark, or at least a film.

Most dullness is not damage at all. It is build-up: skin oils, hand cream, perfume, hairspray, sunscreen, soap residue and everyday dust sitting on the nacre and scattering light instead of reflecting it. Pearls also dry out over time, and a strand left unworn for years can look chalky rather than luminous.

The good news is that a dull pearl is often just a dirty pearl. A careful wash and a soft buff will bring back most of the shine.

Assemble a Gentle Cleaning Kit

Before you touch the pearls, gather a few things. Everything should be soft, and nothing should be abrasive.

• Two or three clean, lint-free cloths — microfibre or well-washed cotton
• A small bowl of lukewarm water, comfortable on the inside of your wrist
• A single drop of mild, unperfumed washing-up liquid or baby shampoo
• A soft make-up brush or a clean, unused paintbrush with fine bristles
• A soft towel to work on, so nothing rolls off the table

Leave these in the cupboard: ultrasonic cleaners, steam cleaners, silver dip, ammonia, vinegar, bicarbonate of soda, toothpaste and abrasive metal polishes. Pearls are porous and chemically sensitive. Strong cleaners strip the nacre, and once that layer has gone, no amount of buffing brings it back.

Washing Dull Pearls, Step by Step

Work over a towel — pearls roll, and a dropped strand on a tiled floor is a bad afternoon.

• Mix the solution. Add one drop of mild soap to a bowl of lukewarm water. More soap does not mean more shine; it just means more residue to rinse away.
• Brush gently. Dip the soft brush in the water and work around each pearl in small circles. Pay attention to the drill hole, where grime collects, and to the clasp and any metal findings.
• Keep it brief. Do not soak the strand. Silk thread weakens when wet and trapped moisture can rot it, so clean in sections and move on quickly.
• Rinse. Dip the pearls in a second bowl of clean lukewarm water, or wipe them with a cloth wrung out in clean water. Never hold them under a running tap — the pressure forces water into the drill holes.
• Pat dry, then buff. Blot with a soft cloth, then buff with a clean one using light pressure in the same direction across the surface. This is the step that restores the sheen.
• Dry flat. Lay the strand flat on a towel for several hours, away from radiators and direct sunlight, so any remaining moisture can escape.

Repeat after every few wears rather than waiting for a full clean. A thirty-second wipe-down does most of the work.

Mistakes That Make Pearls Duller

• Soaking overnight, or drying a strand hanging up — the weight stretches the silk.
• Using hot water, which can dull and even crack the nacre.
• Wiping with tissues or kitchen roll; the wood fibres are abrasive.
• Spraying perfume, hairspray or deodorant directly onto pearls.
• Storing in airtight plastic, which dries them out. Pearls like a little humidity.
• Tossing them loose into a jewellery box with metal chains and rings, which scratch them.

When to See a Jeweller

Gentle cleaning works on surface film, not on damage. If the dullness sits under the surface, or you can feel a scratch with a fingernail, the nacre has been cut and no home remedy will help. The same goes for chipped or flaking surfaces, hairline cracks, stubborn yellowing, or a strand that has lost its knots or looks slack between the pearls. Take those to a qualified jeweller for assessment. Restringing on silk with a knot between each pearl is inexpensive and worth doing every year or two for a strand you wear often — it stops the pearls rubbing against one another and turns a potential break into a minor inconvenience.

Keeping the Lustre — Storage, Wear and Styling

Pearls are meant to be worn. The natural oils in your skin keep them supple, which is why an inherited strand left in a drawer for a decade often looks flatter than one worn every week. Make them the last thing you put on and the first thing you take off: perfume and hairspray first, pearls afterwards. Then wipe them with a soft cloth before they go back in the box. Store them separately in a soft pouch or a fabric-lined compartment, away from radiators and sunny windowsills.

Styling-wise, dull pearls cannot be rescued by design, but well-kept ones flatter almost anything. A simple strand over a fine-knit jumper and a plain shirt looks modern; baroque and keshi pearls in mixed shapes work beautifully layered with a fine gold chain. Match the pearl's overtone to your wardrobe — creamy, pink and silver-toned pearls each sit differently against skin and fabric. Try the strand against your neck in daylight before you commit.