Pearl grading and value factors
Pearls vary in value an incredible amount, some can be bought for a few pounds whereas others have been sold for literally millions, so what makes the difference? As with most things in life, the value of different pearls is determined by their individual characteristics and specifically those characteristics that are rare and desirable. Here we’re going to give an outline of these characteristics in order to help you recognise the differences as well as explain how these characteristics then impact on the value of a pearl. Historically there’s been a lot of confusion as to how to categorise pearls due, in part, to the lack of any agreed criteria determining this. Recently though, the GIA (Gemmological Institute of America) has launched a thorough set of guidelines by which to assess pearls and clear up this confusion. We like the system and employ GIA accredited pearl graders ourselves to assess pearls and ensure we know what we’re buying which in turn helps you know what you’re buying. The system works using seven value factors by which to review pearls, these are as follows.
1. Size
Pearl size is measured in mm, across the diameter of the pearl, traditionally given in 0.5mm variance, e.g. 8.0-8.5mm pearls. As with most gems, all else being equal the larger the pearl the more valuable the pearl. Larger pearls are rarer because they need to be grown in big, mature mollusks which are rare in themselves; they also take more time to grow, costing the farmers more. After a certain point (depending on the pearl type) an increase in just one millimetre can double the value of the pearl (or even more with particularly big ones!)
2. Shape
There are loads of trade names for pearl shapes which are still used today, they can be a bit confusing so it’s important to make sure that you’re as concise as possible when talking about pearl shape. The GIA split pearl shapes into round, near round, oval, button, drop, semi baroque and baroque. Baroque pearls are those of random shape, the more baroque, the more irregularly shaped the pearl (the word then went on to help classify architecture, art and music). We’ve given a few examples of the different pearl shape terms below. A rule of thumb when it comes to valuing shape is the more round the pearl the greater its value. Having said that, as with all things, pearl shape really is a matter of taste, some people prefer the unique shapes of baroque pearls, and these can be a bit of a bargain in comparison to round ones, you can compare how two pearls of the same size and type can vary in value depending on their shape in the Jersey Pearl Stringing Room.
3. Colour
Pearls can be one colour, multi coloured, have a body colour and overtone colour and have orient (a rainbow like shimmer on or under the surface of the pearl). Some colours, such as golden, are only achieved when the pearl is grown in an impeccable environment, making them rare and therefore more expensive.
4. Lustre
This is the shinyness or iridescence of a pearl, good quality lustre is essential, without it pearls appear dull and a bit characterless. Lustre quality is directly proportional to the health of the mollusk, the more healthy the mollusk, the more lustre you’ll see on the pearl. When looking at a number of different quality pearls you can easily see the difference in lustre. Pearls with excellent lustre appear to have their own glow which is a result of the chemical make up of nacre and the way it reflects light. Lustre is unique to pearls, no other gems have lustre and we feel it’s the most important characteristic of all.
5. Surface Quality
Any blemishes affect the surface quality; this can be in the form of small dots, large cracks or blisters. Many pearls are circled or ringed which, depending on your point of view, can be seen as a blemish or a lovely feature, having said that any blemish will lower the value of a pearl.
6. Nacre Quality
This is essentially the thickness of the nacre, if it’s too thin, i.e. the mollusk has been too unhealthy or not given enough time to coat the nucleus, then the nucleus can be seen through as a dark area or it will chip away when drilled and strung. Very thin nacre makes the pearls look chalky, they have little to no lustre because you can see the bead rather than the lovely light reflecting nacre.
7. Matching
The more the pearls match in relation to the above characteristics, the proportionally higher value the string or pair of pearls. This is not applicable when different pearls are intentionally used to create a stylistic piece of jewellery. Therefore we often judge matching on the overall charm of a piece of jewellery rather than exact properties meaning that pearls of different but complementing baroque shapes can be classed as well matched. This is most relevant when it is obvious that the jewellery designer has tried to match the pearls, if they’ve done a good job then they’ll have had to expertly go through a huge number of pearls, this understandably adds value to the end product.
So when you start to look at different pearls you’ll know what to look for, it takes a while to start seeing the differences and reflecting those differences into value so we always recommend that you buy them from someone you can trust, whether it be a well respected brand of pearls or perhaps a jeweller whose opinion you value. The most important thing though is to make sure that you’re happy with the pearls. Just because someone only likes perfectly round pearls doesn’t mean to say that you will. However it is important to make sure that you’re paying a fair price for what you like.
Looking after your pearls
Pearls are surprisingly robust, they can stay looking their best for centuries. However, if they’re not looked after, they can dry out and lose their colour or lustre. The best way to take care of them is just to wear them, which is great. This is because they’re organic things and so absorb the natural oils from our skin which keeps them looking nice for years. They can also be treated with special cleaning kits to keep them looking tip top even if you haven’t had the chance to wear them for some time.
It’s very important to say that pearls are highly sensitive to perfumes and hair spray as the chemicals in them dissolve the nacre turning them horrible and brown which, unfortunately, is irreparable damage. Therefore they should never be sprayed with either. It’s ok to wear perfume when wearing pearls, just make sure that you put the perfume on at least 5 minutes before putting your pearls on and try to spray it away from where your jewellery goes.
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