Understanding the Two Families of Pearls

Pearls are the only gemstone grown by a living creature, and the two types you will meet most often in a jeweller's window come from very different homes. Freshwater pearls are cultivated in mussels living in lakes, rivers and ponds, while saltwater pearls grow in oysters in bays, lagoons and open ocean. That single difference in environment shapes everything else — size, shape, lustre, price and the way a piece feels when you wear it. Knowing which is which makes choosing a first strand or pair of earrings far less daunting.

Where They Come From and How They Are Grown

Freshwater pearl production is dominated by lakes and ponds in China. A single mussel can be nucleated with small pieces of mantle tissue and may produce anywhere from a dozen to more than thirty pearls in one growing cycle. Because these pearls form around soft tissue rather than a hard bead, most are solid nacre all the way through — a genuine advantage for durability, since there is no bead to show through if the surface wears.

Saltwater pearls are grown with far more patience. Each oyster is seeded with a mother-of-pearl bead plus a sliver of tissue, and it will usually yield just one pearl. The main varieties are:

• Akoya — grown in Japan and China, typically 6–9mm, celebrated for a sharp, mirror-like lustre.
• South Sea — from Australian, Indonesian and Philippine waters, 9–20mm, in creamy white and rich gold.
• Tahitian — from French Polynesia, 8–18mm, prized for peacock, pistachio and aubergine tones.

Because each oyster gives so little, saltwater pearls are rarer, slower to produce and, inevitably, more expensive.

Shapes, Sizes and Surface

Freshwater pearls arrive in a wonderful range of forms: potato, rice, oval, button, drop, off-round, ringed and true round, with only a small percentage of any harvest being perfectly spherical. Common sizes run from about 4mm to 12mm, with larger examples commanding a premium. Their surfaces often carry small growth marks, rings or tiny pits.

Saltwater pearls are more likely to be round, and they are usually larger and cleaner in appearance. Akoya sit mostly between 6mm and 9mm, South Sea and Tahitian pearls regularly reach 12mm to 15mm, and exceptional pieces go beyond that. A perfectly round, unblemished 14mm South Sea pearl is a serious investment; a similar-looking 9mm freshwater pearl costs a fraction of the price.

Do not dismiss baroque pearls — the irregular, organic-shaped ones. They are often the most interesting pieces in a collection and hide their flaws beautifully in flowing, sculptural designs.

Lustre: The Real Measure of Quality

Lustre is the sharpness and depth of the light that bounces off a pearl's surface, and it matters more than size or roundness. Akoya pearls have the crispest, almost glassy lustre of all, which is why they are the classic choice for a business wardrobe. Freshwater pearls typically show a softer, more satin sheen, although top-grade freshwater pearls can genuinely rival good Akoya. South Sea and Tahitian pearls have a deep, thick, almost buttery glow, thanks to their generous layers of nacre.

Here is a simple test. Hold the pearl near a window and look for the reflection of the window frame. If you can see a clear, defined shape, the lustre is good. If the reflection is fuzzy, milky or chalky, walk away. Always judge pearls in daylight rather than under shop spotlights, which flatter even mediocre stones.

Choosing Your First Piece

Buying well comes down to a few practical checks.

• Ask about treatments. Bleaching, dyeing, irradiation and lustre enhancement are all common and legal, but they should be disclosed — and dyed pearls can fade.
• Check the knots. A good strand has a small knot between every pearl, so a broken thread does not send your pearls skittering across the floor.
• Inspect the clasp. It should feel solid and sit neatly against the skin, particularly on a necklace you plan to wear often.
• Try pearls against your skin at the neckline or earlobe. Warm ivory, cool white, grey, pink and gold all read differently depending on your colouring.
• Spend your budget on lustre before size. A smaller pearl with a brilliant surface will always look better than a large, flat one.

For a first purchase, freshwater pearls offer remarkable value and a relaxed, everyday look. If you want a single classic piece for work and formal occasions, a 7–8mm Akoya strand is hard to beat.

Styling and Caring for Your Pearls

Pearls sit beautifully with almost everything, but a little thought goes a long way. A 40–45cm choker flatters a V-neck and reads as formal; 45–50cm is the classic princess length and works over a shirt or cashmere; 70cm and longer can be doubled or knotted and looks wonderful layered with fine gold chains. Mixed lengths, mixing freshwater with saltwater, and pairing pearls with plain metal is entirely acceptable now — the old rules have relaxed.

Care is refreshingly simple. Pearls are soft and porous, so make them the last thing you put on and the first thing you take off. Perfume, hairspray, sunscreen and household cleaners will dull the nacre over time. Wipe them after wearing with a soft, damp cloth and let them dry before storing them flat in a soft pouch or lined box — not in sealed plastic, which traps dryness and can crack the nacre. Avoid ultrasonic cleaners and any ammonia-based products.

Finally, have a well-worn strand restrung every two or three years. Silk stretches and absorbs oils, and fresh thread keeps a necklace hanging properly and safely for years to come.