Pearls have been used as adornment for 6000 years and we know for example, that a substantial pearl trade existed in China as early as 2500 BC. Their natural beauty which precludes any need for processing, has made them an enduring symbol of love, virtue and purity.
What are Pearls?
A pearl, whether natural or cultured, is formed when a mollusc (usually an oyster) forms a protective layer around an intrusive object - perhaps a grain of sand - which has somehow lodged within it. This layer is made up of a substance called nacre, and is the same iridescent 'pearly' substance that lines the inside of the shell. In chemical terms, this material is calcium carbonate in the form of aragonite crystals.
The main criteria when judging the quality of a pearl are: Colour, Lustre, Shape, Skin quality and Size. When creating a fine piece of jewellery using cultured pearls, much of the art is in using pearls which are well matched for all of these criteria:
Heming's range of cultured pearl jewellery has been selected for its high quality and value. These pieces are ideal for wearing in a wide range of settings ranging from weddings to 'every day use'.
Pearls occur naturally in a wide variety of colours ranging from cream to silver-white to black, and in some cases can be artificially dyed to induce a specific colour. GemCat only offers pearls whose colour has arisen naturally and our collection focuses on the most popular creams and whites.When describing a pearl's colour we describe the body colour first, before mentioning any overtones that are reflected across the surface of the pearl. All pearls have these overtones when you examine them closely, and they are due to the iridescent nature of the nacre.
Advice on Pearl Colour
The most important aspect of colour when purchasing more than one pearl is to make sure that they are a good match. It is our aim to ensure that for any given colour or overtone the pearls in our range are well matched for colour.
Lustre refers to the intense reflective shine that a pearl produces. The depth and quality of this lustre is determined by the thickness of the nacre which has formed around the pearl's nucleus. The longer a pearl is allowed to grow, the more fine layers of nacre will have time to form concentrically around the nucleus, and the more beautiful the lustre will be. Lustre can be rated from 'very high' to 'very low.
Very High High Medium Low Very Low
A pearl from the lower end of the scale will simply look dull, and usually monochromatic with little or no reflective qualities. They can be produced very cheaply as they take less time to grow and can be sold very cheaply too.
Advice on Pearl Lustre
At Heming we do not believe it is worth compromising beautiful lustre. We only accept pearls from the top end of the scale featuring either 'very high' or 'high' lustre. We ensure that pearls are well matched for lustre as well as colour.
Given the formation process of pearls it is not surprising that they rarely occur in completely round form. The majority of pearls are off-round or 'baroque' in shape. The degree to which a pearl varies from the round form is another of the important criteria by which we judge its quality. Perfectly round pearls are extremely rare, highly prized and therefore carry a significant premium.
The table below demonstrates some of the varying shapes in which pearls may be found.
Round Mostly Round Off Round
It should be noted that some off-round shapes, such as 'tear' or 'pear'-shape pearls can also be highly prized particularly if a matching pair can be found. It is the uniformity of the shape that counts.
Advice on Pearl Shape
The shape of pearls within a strand should be reasonably uniform. The emphasis is on making sure that pearls are well matched, whatever shape they are. At Heming we only offer pearls that are 'all round' or at least 'mostly round'.
Pearl Skin Quality
As with all gemstones it is extremely rare for a pearl to be flawless. It will usually have small surface blemishes variously described as blisters, spots or indentations. The fewer there are, the rarer and more valuable the pearl will be.
It should be emphasised that these are not 'damage' marks but simply by-products of their formation process which emphasise the uniqueness of each pearl.
Flawless Lightly Spotted Spotted Heavily Spotted
These imperfections are markedly less visible when a pearl has a fine lustre and can be further hidden by strategic placement of a drill-hole when the pearl is being mounted or strung.
Advice on Pearl Skin Quality
Heming selects pearls only from the upper two categories. Minor blemishes are just part of the natural formation process and we prefer to focus on the quality of lustre. This, along with the craftsman's skill, will make any blemishes less noticeable.
Pearls are measured in millimetres. The figure refers to the diameter in the case of round pearls, or length and width in the case of baroque ones.
What determines size?
The most important factor in determining a pearl's size is the type of mollusc in which it grows. A large pearl for one species may be unusually small for another. Refer to types of cultured pearl for more information.
The other factors which influence size are:
- the size of the nucleus introduced to initiate the pearl. To create a large pearl a larger nucleus must be introduced. There is a risk that the recipient mollusc may reject it and die before a pearl has grown. There is also a greater chance that the resultant pearl will feature large blemishes. Larger pearls are relatively rare especially with fine skin quality, and the risk in growing them makes them more expensive.
- the length of time a pearl is allowed to grow. The more layers of nacre that are deposited the larger the pearl will become.
Advice on suitable Pearl Size
When choosing pearls for someone, bear in mind their personal style. From a fashion perspective, pearls of over 8 mm are considered fairly dramatic, pearls below 6 mm are considered petite whilst the 6-8mm range is seen as classic.
It is important to care for your pearls to preserve their beauty. Although frequent wearing is advisable as the body's natural oils help keep them lustrous, pearls are sensitive gemstones.
Pearls are vulnerable to some cosmetics and hairsprays, which may contain corrosive acids. They should be wiped frequently with a soft cloth which should help prevent a build-up of these chemicals. A good habit is to put pearls on last before going out or at least after cosmetics and perfumes have been applied.
As with all your jewellery, try to keep your pearls separate from other precious materials or gemstones that might scratch or dull their surfaces. Pearls are extremely compact but rate only 3-4 on Moh's scale of hardness making them vulnerable to abrasion. Regular re-stringing is also advised to avoid losing pearls in the event of a string breaking.