Pearl: meaning, natural and cultured pearls, care

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A pearl is an organic gem formed by a mollusc in layers of nacre. Natural pearls are very rare; almost all pearls on the market are cultured.

Key points

Colours	white, cream, rosé, golden, grey, black (Tahiti), iridescent overtones
Nature	organic gem: calcium carbonate (aragonite) and conchiolin, in layers of nacre
Mohs hardness	about 2.5 to 4.5
Origin	marine or freshwater molluscs (pearl oysters, mussels)
Main types	Akoya, Tahiti, South Sea, freshwater
Sensitivity	acids, perfumes, sweat, lacquers, heat
Tradition	purity, wisdom, the moon, marriage

What is a pearl?

A pearl is a gem of animal origin. When a foreign body or an injury irritates the mantle (the tissue) of a mollusc, the mollusc secretes nacre around the irritant, layer after layer. Nacre is made of tiny crystals of calcium carbonate (aragonite) bound together by a protein, conchiolin; its iridescent reflections come from light passing through the layers.

There are three kinds:

natural pearls: formed without human intervention, extremely rare today. The Persian Gulf was formerly their main source; today, natural pearl fishing is mainly limited to Bahrain;
cultured pearls: a farmer introduces a graft (sometimes with a nucleus) into the mollusc. These are real pearls, and they make up almost all the pearls on the market;
imitation pearls: beads of glass, plastic or shell coated with a shiny finish. These are not pearls.

History

Pearls are among the first gems known. Several ancient civilisations prized them, from India to Rome. Pliny the Elder recounts the very famous but doubtful anecdote of Cleopatra dissolving a pearl in vinegar. In early 20th-century Japan, Kokichi Mikimoto, Tokichi Nishikawa and Tatsuhei Mise developed the modern cultivation methods, building on earlier work by the British biologist William Saville-Kent; sources differ on each man's share. Cultivation brought the price of pearls down and made them accessible.

Traditional symbolism

In many cultures the pearl is associated with purity, with wisdom born of trial (the grain of sand that becomes a pearl), and with the moon. It is traditionally given for weddings and wedding anniversaries (thirtieth anniversary: pearls). The pearl is the June birthstone in Western lists.

These associations are cultural, with no medical or predictive value.

Traditional correspondences

Area	Most commonly cited association
Chakra	crown or heart, depending on the author (see crown chakra)
Element	water
Signs	Gemini and Cancer, according to birth lists
Keywords	purity, wisdom, serenity

How to use it

In a necklace, bracelet or earrings: its softness suits elegant jewellery.
In a ring: better suited to special occasions than to everyday wear.
As a wedding or birth gift: a small pearl is a classic present.

Put it on last (after make-up, perfume and hairspray) and take it off first.

Care and purification

Pearl is soft (2.5 to 4.5) and made of calcium carbonate, which acids attack (vinegar, lemon, acidic sweat, some perfumes). Heat dries it out.

Wipe with a soft, slightly damp cloth after each wearing.
No household products, no ultrasonic cleaners, no steam.
Store it separately, in a soft cloth (not in an airtight plastic bag).
A necklace should be restrung every few years, with a knot between each pearl.
Symbolic cleansing: gentle smoke or moonlight; avoid salt and intense sunlight (see cleansing and recharging your stones).

Recognising a real pearl and avoiding imitations

A real pearl (natural or cultured) feels slightly grainy when gently rubbed against the edge of a tooth, whereas an imitation in glass or plastic is perfectly smooth. Real pearls are all a little different from one another, and the drilled hole is clean, without flaking paint.

Imitations: glass coated with "essence d'Orient" (made from fish scales), plastic, moulded shell; some very well-made imitations, known as Majorca pearls, also exist.
Dyeing or bleaching: most cultured pearls are lightly treated; black pearls may be dyed.
Cultured pearls: do not confuse them with imitations. They are not fake, simply grown.

Only a laboratory (X-ray) can tell a natural pearl from a cultured one with certainty.

Main varieties and how to choose

Type	Mollusc	Character
Akoya	Pinctada fucata	small (about 2 to 10 mm), round, white or cream, very lustrous
Tahiti	Pinctada margaritifera	grey to black, green or blue overtones
South Sea	Pinctada maxima	large, silvery white or golden
Freshwater	freshwater mussels	often without a nucleus, varied shapes, affordable price

Look at the lustre (the shine), the surface, the shape and the thickness of the nacre. Freshwater pearls are the most accessible; Tahitian and South Sea pearls are the most expensive. For a set of soft stones, pair it with moonstone or mother-of-pearl.