As a staples in every woman’s jewellery box, pearls are known as a classy, elegant gemstone. Pearls are iridescent organic gems that are created within an oyster. An oyster covers a foreign object, like a grain of sand, with beautiful layers of nacre. Pearls used to be important financial assets. Thousands of oysters had to be searched for just one pearl. However, in modern times, harvesters can now implant grains of sand within a mother oyster, creating an affordable pearl. Pearls are no longer an act of chance.
And the beauty of pearls isn’t left to chance either.
Fine quality pearls are at the height of their beauty the moment they are removed from the mother oyster. Such pearls require no lustre or colour enhancement prior to setting as jewellery. However, pearl enhancement is a common practice that makes attractive jewellery accessible to a wider market.
The basic treatment on pearls would be:
Pearls can be treated with light
Processes such as light chemical treatments may improve the appearance of a lower quality pearl. Light processing will improve lustre, and does not damage the pearl’s structure. However, heavy chemical treatments may adversely affect the physical integrity of a pearl and can sometimes impart a coarse and chalky look and feel.
Pearls can be bleached and dyed
Pearls are soft, porous and accepting to all contact with natural and chemical substances, such as dyes. Pearl treaters take advantage of this porosity to achieve finer, more uniform colours with natural extracts and inorganic and/or chemical dyes. Most pearls are bleached to lighten uneven dark areas that may appear under the nacre. This is permanent, provides a more uniform appearance and prepares the pearl for steps that can enhance the colour. Irregular pearls are dyed to provide colours that are rare and to make it easier to create a matched strand. It may take a producer of Tahitian pearls two to three years to accumulate sufficient matching, natural-coloured pearls to string a necklace. The next option is to dye pearls instead of waiting for three years.
Pearls can be treated via gamma rays
Gamma-ray irradiation darkens the nucleus and results in darker pearls, sometimes dark enough to resemble natural colour black South Sea pearls. The advantage, of course, is they can be sold for much less. Irradiation also enhances orient (the display of iridescent colours) in some pearls. The pearls retain no radioactivity making the enhancement considered harmless.
Pearls can be coated
Pearls can be coated to enhance their lustre. A clear lustrous coating is applied to the pearl, which improves it temporarily, but with time and use the coating may peel off showing the inferior lustre underneath. The coating can be detected by the feel or where the coating has peeled off. Under high magnification the coated surface will look very smooth in contrast to the natural, scaly look of the nacre.
Pearls can be tumbled
Cultured pearls are also washed and polished by tumbling them in a concentrated water and salt solution that’s abrasive enough to remove any mucus or tissue that clings to the cultured pearls’ surfaces. This is usually followed by chemical treatments that bleach the cultured pearls to make them white.