The art of recognising quality pearls
Most of us know the 4 C’s of diamonds and the different karats of gold but can you consider yourself a real pearl connoisseur?
Pearls are one of nature's most intriguing phenomena. A mollusk will defend itself against foreign matter by creating a calcium carbonate (Nacre) pearl sac around the intruder. As time goes by, the mollusk will continue to add layers to the pearl sac resulting in an increasingly larger pearl. In Jewellery, pearls are identified by the type of mollusk species and the region in which they are found/harvested. Given the extreme rarity of naturally occurring pearls in the industry, we will focus more on the four major types of cultured or ‘farmed’ pearls.
- Freshwater - Freshwater mussels have the unique ability to produce multiple pearls per harvest making them the most economical. Harvests will average 24-32 pearls per mussel and will spend less than a year to grow to maturity. Sizes will range from 4-12mm.
- Akoya - Akoya pearls began in Japan, the birthplace of cultured pearls. They are considered the ‘Classic’ pearl consisting of white or cream coloured nacre with rose, silver or cream overtones. Akoya’s are harvested after 9-16 months and each mollusk will yield 2-5 pearls. Sizes range from 3-9mm
- Tahitian - Cultured Tahitian pearls are one of the latest technical developments among the pearl family. In the 1960’s, Jean-Marie Domard modified Japanese culturing methods to use on the Black-lipped oyster. This oyster produces a charcoal silverish colour of pearl and is found in the French Polynesia. This oyster can grow rather larger enabling for larger than average pearl size. Harvest time for tahitian pearls are 2-3 years to produce one pearl per oyster.
- South Sea - South Sea pearls are some of the rarest pearls to be found in jewellery. The oysters are much larger than average and yield spectacular quality large pearls. The size ranges from 9-20mm with a nacre thickness from 2-6mm. To put that in perspective, the nacre thickness of recent akoya pearls range from 0.35-0.70mm.
Figure 1 : Vintage 3 strand Japanese Akoya cultured pearl and diamond clasp bracelet
Pearl colours are defined by two characteristics, the body colour and the overtone. The body colour is defined by the main colour of the pearl which is usually based on species type and water conditions. The overtones are translucent colored films, often rose or green, visible on the surface of the pearl. They can affect the visual depth and glow of the pearl. These overtones can be enhancements, with the trade demanding this visual effect. Beware ! Nice quality estate pearls, which have been cared for, can be a beautiful addition to one's jewellery collection!
Lustre is the ‘shininess’ of the pearl. The brilliance and reflectivity are the characteristics under evaluation here. Lustre is a key element when differentiating between saltwater and freshwater pearls as the saltwater will typically ‘shine’ significantly more than freshwater.
Figure 2 : Tahitian pearl and diamond ring in platinum
Pearls come in many various shapes from button to baroque to perfectly round. For the most part this is a matter of style and taste although perfectly round pearls are the least common giving them the highest price tag.
As one might be able to guess, a smooth surface is ideal. Any bumps, spots or discolorations can affect the quality of the pearl.
Figure 3 : Vintage South Sea pearl and diamond earrings
The larger the pearl, the longer it has spent in the shell of the oyster or mollusk. This combined with the fact that the larger species of oysters can only produce one pearl at a time make larger pearls much more rare than the smaller more commercial ones.
New mass production techniques have allowed jewellery manufacturers to flood the market with more product than ever before. As the techniques are refined and optimized for profits, quality is pushed to the side. Pearls are no exception. Older cultured pearls have a tendency to have a much thicker nacre, which is crucial to pearl quality.
That’s it for this short segment about pearls. If you love pearls as much as we do, feel free to check out our wide selection on our website or stop by our store in westmount to see the entire collection!