Natural pearls are quite rare because they’re a random product of nature that occurs less and less frequently due to pollution and over-fishing. You can readily buy cultured pearls, however; which are natural pearls created with human assistance.
Both natural and cultured pearls form from an irritant that molluscs protects themselves from by secreting successive layers of nacre, which is an organic substance composed of aragonite and conchiolin. Imitation, faux or stimulated pearls do not possess nacre; they are usually glass, plastic or shell beads dipped in ground up fish scales and coated with a lacquer.
Natural pearls are extremely rare and outrageously expensive, so you’ll probably be looking at types of cultured pearls. Familiarise yourself with the different types: saltwater South Sea, Black Tahitian and akoya pearls; and freshwater pearls.
When judging pearls firstly consider nacre. Natural saltwater and cultured freshwater pearls are solid nacre, while cultured saltwater pearls have a nucleus that’s surrounded by layers of nacre. The number and thickness of the layers of nacre is what’s important in determining the quality of a pearl. And, in turn, this produces the inner glow of a pearl; the soft, satiny sheen — its lustre — which will influence its value.
Check out the colour. Pearls come in a wide range of colours and you should consider a pearl’s main body colour, its overtones (say, a white pearl with gold or rose overtones) and its orient (iridescence), which means the play of light interference across the pearl’s surface or just beneath it. Natural colours are best, but you can also buy pearls dyed various colours.
Pearls are graded according to the smoothness of their surface. Blemish-free pearls demand a premium; small spots on a pearl don’t decrease the value as much as chips or cracks.
Round or spherical shapes are most desirable. But pearls can look beautiful in all sorts of shapes. If you’re having a necklace or bracelet made ensure you have matching shapes and sizes.
Generally, the larger the diameter of a pearl the more expensive it will be. The price of a pearl increases exponentially as its size increases.
Pearls can be graded on one of two scales. No standardised, industry-wide pearl grading system has been established, but your jeweller may use one of two commonly used grading systems: the AAA-A and the A–D systems. If your jeweller refers to a grading, for example AA, ask exactly what he or she means by that. Ask if you can read a description of each grading term so that you know what each term used means.
Pearls are soft (3 on Mohs’ scale, which measures a gemstone’s resistance to scratching) and they’re porous, so be prepared to look after them. Necklaces and earrings are a safer option than rings or bracelets, which are more easily damaged when you wear them.
Always get a detailed certificate of authenticity with your purchase. A certificate states the quality of your pearl and contains a detailed description of your jewellery, which is handy in case you ever need to make an insurance claim.