Organic · Nacre over a bead, grown in an oyster
Pearl
The only gem produced by a living animal, graded on a coating whose thickness you cannot see and which decides everything.
Why thickness decides the life
Nacre is aragonite platelets bound in conchiolin, a protein. It is beautiful, slightly porous and slightly soluble in acid. A thin coat loses its outer layers to skin acid and cosmetics, going dull, and develops fine cracks as the protein dries, which ends in visible peeling at the drill hole. A thick coat can be worn, cleaned and polished by contact for decades and looks better at forty years old than at four.
Lustre, which is layer order
What reads as lustre is the regularity of the aragonite layers. Well ordered platelets reflect light coherently and produce a sharp, tight reflection with a visible source. Irregular layers scatter, which gives a soft glow that never resolves into a reflection. Sharp lustre generally means a good pearl, with one important exception: surface polishing can flatter a thin nacre into looking brilliant in shop lighting.
Matching, which is most of the price
A strand requires pearls that agree in size, shape, colour, overtone and lustre, and the sorting required to find fifty that match is enormous. That labour, not the pearls themselves, is the reason a strand costs several times the sum of its parts. Judge a strand by looking along it at eye level: any pearl that pulls the eye is out of match.
The types
Type determines nacre thickness far more reliably than price does.
How to check it
- The tooth test. Rub a pearl gently along a front tooth. Nacre feels faintly gritty, glass and plastic feel smooth.
- Look into the drill hole with a loupe. You can often see the boundary between nacre and bead, and always whether it is chipping.
- Roll the strand under a point light. A sharp, tight reflection means ordered layers.
- Ask whether the colour is natural or dyed, particularly on dark and golden pearls, and ask for it on the invoice.
Care
- Pearls go on last and come off first. Perfume, hairspray, hand cream and sweat all attack nacre.
- Wipe with a soft damp cloth after every wearing.
- Never ultrasonic, never steam, never a chemical cleaner.
- Do not store in a sealed plastic bag. Nacre needs a little humidity or the protein dries and crazes.
- Restring on silk with knots between pearls every one to two years of regular wear.