If you are thinking of investing in pearls you need to be aware of six main factors that determine their quality and value. All these factors are important but you may need to make compromises in your choice if you need to keep your purchase within a limited budget. In order to prioritize those ‘inevitable compromises’ I have made this list in order of importance.
1. When evaluating cultured pearl ‘nacre thickness & quality’ is usually considered to be the most important factor because this will determine how long the pearls will last. The nacre is the white substance secreted by the oyster around the pearl thereby creating its lustrous pearly coating that is so highly prized. The thicker this coating the longer the pearl will last and the better the quality of that coating the greater the lustre and iridescence will be.
2. Closely associated to the quality of the nacre is the ‘lustre & orient’ of the pearl. This refers to the sharpness and intensity of the reflections on the pearl’s surface. It is not just the shiny reflective area but also the shadow area which gives a deep iridescent glow like no other gem.
3. Colour is a very important factor when evaluating pearls. There are effectively two parts to the colour of a pearl and these are known as ‘body colour’ and ‘overtone’. The body colour refers to the overall look of the pearl ie. white, pink or black etc. The overtone is the more subtle secondary colour that can be seen. For example a pearl may be seen as basically white but also has a subtle pinkish overtone. These are highly prized and more expensive. Others may be white but with a creamy overtone. If the creamy overtone is very strong the value of the pearl reduces. Cultured pearls are available today in a great many colours but not all of these colours are natural as some are produced with dyes or irradiation techniques.
4. Another factor that will determine value is the quality of the surface texture of any pearl. Blemishes or small blisters or spots will affect the value. It is difficult to find perfection in nature but if a pearl has a clean, smooth surface without any marks it is clearly going to be more valuable than one with many unsightly blemishes.
5. Basically there are three different categories in considering the shape of a pearl. These are ‘spherical’, ‘symmetrical’, and ‘baroque’. The round ‘spherical’ variety of pearl are the most rare and so these cost the most. The more perfectly round they are the more expensive they become. Button-shaped and pear-shaped pearls come under the ‘symmetrical’ variety and their value will be determined by how symmetrical and well proportioned their shape is. Symmetrical pearls are less expensive than round pearls but more expensive than ‘baroque’ pearls which are pearls in our third category – those with a totally irregular shape.
6. Finally, as with other fine gems, size is an important factor too. Natural pearls are sold by weight whilst cultured pearls are sold by their size in millimeters with reference to their diameter. For pearls that are not round two measurements are normally given for both width and length. The larger the pearl the rarer it is and therefore the more valuable it becomes. There is a dramatic increase in the price for pearls that are over 7.5mm.
One other thing worth mentioning, but not included in our list above, is the ‘make’ of the pearls. The make refers to how well matched a string of pearls is, for example in a pearl necklace. Each pearl must be selected to match size, shape, colour, lustre and surface blemishes so that the overall string looks beautifully uniform in all respects. This is no easy task!