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How to Understand Grading Systems of Freshwater Pearls and Saltwater Pearls

When you are reading gradings of pearls, AA, AAA and even AAAAA, are you confused at all these grading values?

Although different companies use various grading systems, they apply the same basic principles to their grading systems. There are three key elements that are used to evaluate the quality of pearls. They are: Shape, Flaws, Luster and thickness of nacre.

• SHAPE of pearls: the rounder the better mainly for non-beaded freshwater pearls. But the rounder the higher grading for both freshwater pearls and saltwater pearls.

Perfect round shape is common and a must have for most of saltwater pearls, because they have bead nucleus as a perfectly round template to form their nacre over. So, baroque shapes of saltwater pearls stand up among all these round saltwater pearls.

On the contrary, perfect round shape is rare and valuable for freshwater pearls, because freshwater pearls are non-beaded cultured pearls. The formation of their shapes is out of human control. As a result, round shape is rare and valuable among freshwater pearls.

In 2010, a new type of freshwater pearls called Edison Pearls was successfully produced and came to the market with the development of culturing technology of freshwater pearls. Same as saltwater pearls, Edison Pearls are nucleated with perfect round bead nucleus. Therefore, perfect round shape is common among Edison Pearls.

The non-beaded freshwater pearls with perfect round shape are normally half drilled and used in rings and pendants. They are usually sold as loose pearls in whole market. The high-quality non-beaded freshwater pearls that are used in necklaces are round, NOT off-round, although they aren't perfectly round. 

• Flaws in surface: the less flaws the better and the higher grading for both freshwater pearls and saltwater pearls.

Most of time, it is very difficult to avoid very minor flaws which are almost invisible or unnoticed on one or two pearls in pearl necklace, even in high-quality pearl necklaces. It is because, firstly, the whole formation process of pearls is almost natural except the insertion step at the very beginning of the process; secondly, all pearls are screened, filtered and categorised by hand.

• Luster, the more lustrous the better and the higher grading for both freshwater pearls and saltwater pearls.

With the development of pearl culturing technologies, high-quality freshwater pearls have the same strong luster as saltwater pearls. 

The correct way to examine the strength of pearl luster is to look at pearls in natural day light setting, or normal office indoor light setting (400 Lux, 3500K). The lighting specially designed for jewellery can over-expose the luster of pearls which can create a exaggerated luster and false reflection from pearls.

These three criteria above are the only factors used in the grading system of pearls. When the pearls are rated at the top grade, AAA or AAAAA or what so ever, they are almost perfect in round shape, flaws in surface and luster. The pearls in the lower grade always have some imperfection in one of these factors.

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These three criteria are also important factors to evaluate the value of pearls. Besides that, there are two other factors that can affect the value of pearls. They are thickness of nacre and size.

• Thickness of Nacre: the thicker nacre the better and the more valuable for saltwater pearls and Edison Pearls.

This criterion doesn't apply to freshwater pearls because they are of 100% nacre. Basically speaking, the longer culturing time pearls have, the thicker nacre they can form. The nacre layer of South Sea Pearls, Tahitian Pearls and Edison Pearls have more than 1.2mm thick because their culturing time is more than 5 years long. Akoya Pearls only have less than 0.8mm nacre because they are being cultured for around 18 months. So it is not rare that the nacre layer of Akoya pearls crack and even peel off. So it is important to ask your dealers about the thickness of nacre layer of Akoya pearls when you purchase them.

• Size: the bigger the more valuable for both freshwater pearls and saltwater pearls.

This can only be true when the pearls have similar quality in their shape, flaws in surface and luster. Small pearls can come to the top grade when they perform well in shape, flaw in surface and luster.

These two criteria don't apply to the grading system of pearls although they are important factors to evaluate the value of pearls.