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How to recognize a pearl’s quality. Part 1: nacre thickness

Combining a Cortez Pearl with the skills and design of Carlos CabralWe now commence a new blog-delivery with a new subject: pearl quality.  How can we view this from the client’s standpoint?  Let us ask the following questions: Why should it should I pay more for higher quality?  What do I get in exchange?

And the answer should be clear and concise: quality gives you value and beauty.  In the case of gems this should be of real importance, because these products must keep their beauty and their value in 5 or 10 or 200 years.  A gem that loses its beauty also loses its value

How can we measure pearl quality?  That is a very interesting question and one we hope to be able to answer in an easy and precise manner.  In the meantime, we will tell you about a critical indicator of pearl quality: nacre thickness and we will see why this indicator is this so important.  But first let us begin this post with a couple of stories…

A Life Investment

Beautiful Hindu Woman wearing a lot of jewelry
Beautiful Hindu Woman wearing a lot of jewelry

For millennia, human beings have purchased precious stones and metals, as well as jewelry and ornaments – made with these materials- for their personal use and enjoyment.  Jewelry items are not only used as adornments or to establish “status” amongst people; they can also serve as a manner of “safe-guard” in moments of crisis.  As an example, in many countries women adorn themselves with lots of jewelry and this can be of a great advantage at times: imagine that at moments of social unrest or economic struggle, that a family has to flee for their lives, keeping only what the family is wearing? Of course, you may own a pair of fancy tennis shoes, but that will not be enough to feed the family or pay a ransom, but your mother’s jewelry may be enough to help the family get on its feet again.  Of course there’s also the question of quality: it would be better to possess a single high-quality –valuable- item, than 20 kilos of costume jewelry (it will not even allow you to run faster). Under this logic let us examine a relatively well documented case.

On October 1917 -during the Russian revolution- the new Bolshevik government began arresting all Russian nobility. This meant that the aristocrats fled their country, leaving behind their palaces, land, clothes and furniture, keeping with them only those items which had great value and were easily carried and hidden.  Amongst these Russian nobleman was Prince Alexander Yousopoff (better known for his part in the assassination of Rasputin) who fled to Paris with some family jewels.  Amongst his most precious treasure he had a pearl necklace (that some assumed had many Sea of Cortez pearls, due to the voracity Russian nobility had for fine pearls) that might have belonged to his mother, Princess Zenaida Youssopova. During his final stay in France, his economic problems became greater and finally –in 1922- he decided to sell this pearl necklace (it might be the one that appears in his mother’s portrait, although without the famous “La Regente” pearl, also known as “Napoleón’s Pearl”, because this pearl has its own unique story). The sale was done by prestigious jeweler Pierre Cartier, who was able to sell the pearl strand to a rich American heiress at a value of $400,000 U.S. dollars.

Princess Zenaida Yusupova, wearing "La Regente" Pearl and an incredible pearl necklace.

To be honest with you all, this story might have some contradicting leads (which I believe just adds a detectivesque flavor to it) and you may want to dig deeper into the story…just like treasure hunting.  Some -like this reference- lead us to think that the pearl necklace might have originally belonged to Catherine “The Great” of Russia, but the necklace could’ve been part of the Imperial Russian treasury, although it is said but the jewelry was found by the Bolsheviks, hidden within a  wall in one of the imperial palaces of the Romanov dynasty. In order to have a more coherent story we are using the information found in the “Cortez Pearl” website as valid.

Nacre thickness and pearl quality

For us, one of the main attributes to take into consideration is nacre thickness.  To understand what this is all about, we can ask the following question: How much of your pearl is really pearl?  Let us analyze this.

Most marine –or salt-water- cultured pearls are produced by the introduction of a small shell-bead –by means of a special surgery– inside the pearl oyster’s body, and over a length of time –the culture period- the little bead will become coated by millions of thin nacre layers, deposited one over the other (in the likeness of an onion) until the pearl is harvested. Under a short culture period (4 to 8 months) the pearl will have a thin nacre coating, but under a longer culture cycle (18 to 24 months) they will possess an excellent nacre coating.

X-Ray of a Cortez PearlHow can we make sure that we have a good nacre coating on our pearl?  There are several way to find out, amongst these we have:

  1. X-Rays: these are used to observe the shell bead within the pearl, and we can also measure the pearl’s nacreous thickness. This is a method that is employed by many pearl producing countries, such as Tahiti.
  2. Cutting the pearls in half: we select a sample of pearls that will be cut in half to analyze their nacre thickness. This is the best method to determine nacre thickness…but it might be a bit destructive for most people.
  3. Inspection of the drill hole: this is a difficult method to use and that will not ensure you of the pearl’s nacre thickness, but it does help to identify pearls with a thin nacre coating.

Additionally, we have indirect methods that may be utilized by  different pearl farmers.  We utilize a simple technique which provides us with very good information regarding nacre thickness: we utilize a group of control oysters in wish we only insert shell beads with a single size.  Thus at the end of the culture period, we can measure the harvested pearls and determine their nacre thickness by means of the size difference between the shell bead and the resulting pearl (if we use a 6 mm shell-bead or nucleus, at the moment of harvest the pearls will at least measure 8.2 mm), but we can also gauge both the maximum and minimum nacre thickness in a given lot of pearls.  Utilizing a combination of these methods we can feel assured of the nacre quality of our cultured pearls.

Harvest 2010- Nacre Thickness

We feel are grateful for this year’s harvest especially with the resultant nacre thickness, which was excellent.  The range we consider typical of a Cortez Pearl is a minimum of 0.8 mm, with an average thickness of 1.2 mm and, in a rare occasions, exceeding 2.2 mm.  With this nacre thickness, Sea of Cortez pearls are just as good –and sometimes better- as most South Sea pearls in the market today.

In the image above you can appreciate the nacre thickness of a group of pearls that was cut in half to evaluate their nacreous coating. Those with a thinner coating (left side) have a thickness of 0.9 mm, the average ones (central portion) measure 1.5 mm and the thicker ones (on the right side) may even reach up to 2.8 mm (in all instances I am just mentioning the thickness on one of the pearl’s sides, as seen in the following photo).

Pearls in Half

Sea of Cortez pearls: Our guarantee

A case of Pearl Leprosy?

A thick nacre coating means that the pearl has what it takes to display good natural luster -thus it will not be necessary to polish it- and for the pearl to have durability -to endure the passage of time- and to become a family heirloom.  On the other hand a pearl with a thin nacre coating will seem dull and unappealing –unless the pearl is polished- lacking real beauty and devoid of orient, it will not be durable and can easily peel and crack.

The pearl we produce is guaranteed for life against natural defects if the pearl suffers any damage (not due to the wearer), then this pearl will be replaced by another one of the same quality for value. In most instances, any damage from the pearl is caused by the wearer such as scratches, damage caused by jewelers, and –sometimes-even being run over by a car, but these are exceptional cases.

If we take into consideration that a thinly coated pearl can have a “useful life” of only a few months to perhaps a couple of years, then a pearl with a value of $10.00 U.S. dollars becomes an expensive product:

  • $10.00 divided by 8 months = $1.25 per month
  • $10.00 divided by 24 months = 42¢ per month

But if the pearl has a thick nacre coating, then it has the potential of a long, useful life, well in the range of hundreds of years; but since this is something really hard to estimate, let us say that with a lifetime guarantee we are at least talking about 80 years. Thus if we have a pearl valued at $1,000 USD we are talking about a good price:

  • $1,000 divided by 80 years = $12.50 per year = $1.04 per month

So, you get the idea: quality pearls actually give you more of everything. And, now let us go back to our question of “why should we be interested in a pearl’s quality?” but now analyzing it from the viewpoint of the pearl producer: Why should we invest more time to in order to obtain a higher quality pearl?  What do we receive in exchange? The main thing you obtain is prestige to a proven quality and second: it’s a matter of personal pride (you can actually feel good about what you are doing).

Investing in quality is well worth it.  In the future, we will continue to talk about other aspects of pearl quality.