Pearl Education Part 1 - Pearl Grading and Sizing
What affects the value of a pearl?
How are pearls graded?
Unlike diamonds, there isn’t an official grading system for pearls although the Mikimoto system has been adopted throughout the industry. Many companies specialising in the more traditional styles of pearl jewellery do grade their pearls but beware, as there is no official standard, a "AAA" graded strand from one company may be of a different quality to a "AAA" strand from another.
The grading is based on the factors below all of which contibute to the quality (and therefore the price) of a pearl.
Lustre - this is how much light is reflected through the layers of nacre and off the surface of the pearl. A good quality pearl will be shiny not dull so the better you can see your own reflection in it the better the lustre!
Surface Quality – Tiny marks found on pearls are normal, they are after all created by nature and are proof that the pearls are real! Pearls with few or no surface imperfections are the most valuable and a completely flawless pearl is extremely rare.
Shape – It takes years for a cultured freshwater pearl to grow to 7mm or larger, it is nothing less than a miracle if it grows in a perfect sphere! The rarity of a perfectly round pearl makes them the most valuable.
Size – The larger the pearl the more expensive it is as long as it has good shape, surface quality and lustre too! A smaller pearl with fewer blemishes and high lustre will be more valuable than a large dull pearl.
Colour – Pearls are commonly cream, pink and grey (black). The most important factor to remember is that the more expensive the strand, the better colour matched the pearls should be. This is easier with cream pearls as they are the most common, but in fact perfectly matched pearls, particularly if they are pink or black, tend to look imitation.
The final price of a piece of pearl jewellery depends not just on the quality of the pearls, but also how much gold or silver there is in the finished piece.
How are pearls measured?
Pearls are measured across their diameter in millimetres. Freshwater pearls are said to be 6-7mm or 7-8mm etc , this means they can be anwhere between the two measurements. An oval or teardrop pearl is also measured across its diameter but it will be longer than wide so will appear larger than a round pearl of the same size!
A pearl necklace described as 6 - 7mm means that the pearls range in size from 6mm to 7mm. When strung the larger pearls should be in the centre of the necklace and the smaller ones strung towards the clasp. This is unlikely to be obvious to the untrained eye as the change is very gradual!
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A note about our pearl jewellery images. All of the pearl jewellery photographs on our website photos are of the actually jewellery (not retouched or photoshopped!) and have been taken taken at very close range to enable you to see the detail of the item. This means that sometimes the tiniest imperfections which would not be visible to the naked eye may be seen in the image.