What is nacre?

If you have either bought a strand of pearls or done any amount of research on pearls, then most likely, the term nacre has probably come up. And, if you are like most, you just know that the nacre is important – but are not really sure why. In this blog we are going to illuminate why nacre is so important, how it develops, and why it is factored into the overall grade.

Nacre is the outer coating of a pearl. When an oyster is nucleated, the nucleus is irritating to the shell. In order to protect itself from this irritant, the oyster secretes nacre around the nucleus to protect itself from the foreign object. Nacre is also referred to as ‘Mother of Pearl’ and is the same gorgeous and shimmery material that lines the interior of a mollusk.  Nacre is deposited in the thinnest of coatings as the pearl is developing. The layers are actually quite similar to the layers of an onion. Pearls with a short harvest time, tend to have a more thin nacre. Pearls that are allowed longer to cultivate have more layers and therefore a more thick nacre.

Pearls that have a thin nacre may appear beautiful at the time, but as they age, the nacre will wear off thus ultimately removing the luster of the pearl. When this happens, the pearl has a dull and chalky appearance. As a result, pearls that have a higher quality nacre are more valuable and will last significantly longer and maintain their luster in contrast to pearls with a thin nacre.

As we discussed earlier, freshwater pearls are made up entirely of nacre, whereas saltwater pearls have a nucleus with the nacre forming around the nucleus. As a result, the thickness of the nacre is an attribute that applies only to saltwater pearls.

At Seven Seas Pearls, all pearls are rated individually and then each rating is averaged out for a total grade. The rating that Seven Seas Pearls’ uses for the absolute best nacre is “top” from there the nacre is rated Very Thick, Top, Medium and Thin.

Here is an example of the difference between a pearl with top rated nacre and thin nacre – can you see how the nacre dramatically impacts the luster and glow?

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Here is another example of nacre with a less extreme difference between the grades. The pearl on the left has a rating of very thick nacre and the pearl on the right has a rating of medium nacre.

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As you can see from the above images, the thickness of the pearl nacre has a dramatic impact on the overall quality, luster and beauty of a pearl. Check back soon for our next blog on Akoya Pearls!


Why is surface clarity so important for pearls?

When considering a piece of jewelry (pearl, gemstone or diamond) the term “clarity” comes up rather frequently. In past blogs we have explored how pearls are graded and how Seven Seas Pearls grades pearls in contrast to the pearl industry. Surface clarity is a term that is used frequently to describe the overall quality of a pearl – here in this blog we are going to explore in depth why the surface clarity of a pearl is such an important factor to consider when making a pearl jewelry purchase.

The obvious first question is “what is surface clarity” – surface clarity, much like its name implies is how smooth or without flaws the surface of a pearl is. Since pearls are formed by the insertion of a nucleus, the nacre develops around it and results in layers being built around the nucleus. Since the process of nacre layers developing is a naturally occurring process (without human intervention) there is no way to guarantee the quality of the surface clarity. The surface of a pearl can be incredibly smooth – without indentations or flaws or it can be incredibly flawed and have many dents. As we mentioned in a previous blog, like when buying a diamond, it is important to have a balance of all the aspects of how a pearl is graded. If you have a pearl with excellent luster – but poor surface clarity, the pearl will have a dingy appearance. The same would be true with a pearl that had excellent clarity, but poor luster. This is one of the reasons why Seven Seas Pearls grade pearls on each individual aspect and then those ratings are averaged out for an overall grade.

As you are probably very familiar with by now, pearls are graded universally on the AAA grading system. Seven Seas Pearls has added an extra category that describes pearls that have perfect clarity. For perfect surface clarity, this term is AAA Flawless.

Here is an excellent example of how important surface clarity is. Here are two pearls that have the same rating of luster – but as you can see, one has very poor surface clarity (rated A+) and the other has very good surface clarity (AAA Flawless).


As always, extreme differences are easy to see and take notice of. Here is an example of two pearls that are a little closer on the rating scale – even still, it is easy to see the difference in surface clarity and ultimately why they are graded differently. The pearl on the left has a surface clarity rating of AAA and the one on the right has a rating of AA – can you see the difference?

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As you can see, pearls with a higher quality surface clarity allow the pearl’s luster to really glow and reflect the light. As a result, pearls with a high surface quality are more valuable and desirable than pearls with a lower grade.

The next aspect of pearls that we are going to explore is nacre and why it is so important. Check back soon for our next blog.

Why is luster so important for pearls?

If you have been reading our blog, then you have heard us use the term “Luster” – while you can probably guess just from the name what this refers to, in this blog we are going to give you a more in depth understanding as to just what luster is and why it is such an important consideration when purchasing a piece of pearl jewelry.

The obvious question is “what is luster”.

When you hear “luster” it makes it easier to think of it as the amount of light or glow to a particular pearl or strand of pearls. Light is reflected off of a surface, the luster of a pearl refers to how much light as well as the quality of light that is reflected from the pearl. Pearls can have excellent to very pool luster. Pearls with very pool luster appear dull and have almost a chalky plastic appearance. In contrast, pearls with excellent luster will glow and shine. The luster has a dramatic impact on the overall price of a pearl, the reason being that not many women would be impressed with a string of pearls that had the same amount of glow as a bunch of small rocks.

Here is an excellent example of a pearl with excellent and very poor luster – it’s pretty easy to tell the difference isn’t it?


That was an example of two extremes – one pearl with perfect luster – and a pearl with absolutely terrible luster. Naturally there are grade variations in between these two examples. If you remember from previous blogs, one thing that we have highlighted many times is how Seven Seas Pearls’ grading system is different than any other pearl grading system. Ultimately, Seven Seas Pearls grades each pearl on their individual criteria: luster, surface clarity and nacre. Others just give the pearl an overall average grade. With our system, it is easy to see exactly the quality of luster you are receiving. The universal grading system for pearls is the AAA grading system. At Seven Seas Pearls, we have added an extra category for pears with perfect luster. These pearls are given a rating of AAA Gem. The rating scale goes from AAA Gem, AAA, AA+, AA, A+ to A ratings. A pearl with the rating of “A” will have very pool luster. Here are a few examples so that you can see for yourself the difference of pearls with various luster ratings.

For example, here is a pearl with AAA Gem rating (very high) and an AA rating (not so high). Can you see the difference between the glow of the pearl on the left and the pearl on the right?

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As you can see from these above examples, the luster of a pearl makes a huge difference on their overall appearance and beauty. It is easy to see why pearls with a higher grade luster are more valuable than pearls that have poor luster. Check back soon for our next blog on surface clarity and why it is so important.