Nucleation of an Oyster

Nucleation

Nucleation is the process of surgically implanting a spherical “starter” mother of pearl bead into the gonad organ of (in saltwater) oysters or (in freshwater) mussels. It is an extremely delicate operation to slice into the organ without harming the mollusk.

Along with the bead, a tiny piece of mantel tissue that is cut from a donor oyster is inserted next to the bead to start the nacre production. Most of the technicians are women known for their skill and patience…You can see, in this picture, the oyster shell is held open by a clamp and small piece of wood. The implanted shells are then put in netted panels and tenderly cared for while the pearl sac forms and layers and layers of nacre are laid on top of the mother of pearl bead. The minimum time in the water is 6 months, but up to three years for thicker more lustrous nacre. Water temperature and perfect conditions are paramount to the success of a beautiful pearl crop. Weather can have disastrous effects on an entire crop of pearls. Think of this when you hear about cyclones and major storms in the south seas. 

Rare Fijian Saltwater Pearls

Fijian Pearls are grouped in the usual collection of Tahitian Pearls, but they are technically not Tahitian Pearls. They are Fijian Pearls. They are even cultivated in a subset of oyster than the Tahitian Pearls. Tahitians are farmed in the Pinctada Margaritifera oyster, while the Fijian Pearls are farmed in the Pinctada Margaritifera typica oyster. (You may use that in cocktail conversation)

At this farm, in Savusavi, Fiji, the oysters are grown from the very smallest stage of baby spat to a full grown about 8″ oyster. At this stage they are ready to be nucleated and set to work. Nucleation is a very delicate surgical work, done by qualified technicians. A round “nucleus” must be inserted into a very specific part of the gonad organ along with a tiny square of donor mantle tissue. The mantle tissue activates the oyster to start producing a protective covering that is coated over the nucleus. This is to “protect” the oyster.

It takes about 1 1/2 years to grow an oyster to adult. Once the oysters have been nucleated and tied to a rope for operation, they are lowered back into their home waters. Every 6 months they must all be brought to a “cleaning house” to be scrubbed free of hangers on and growths. It looks like a small operation, but it is tidy. Fiji Pearls has different stations all over the Savusavu Bay for cleaning, harvesting, and sorting.

Fiji Pearls is dedicated to a sustainable farm culture and instilling into the Fijian population the importance of respecting and honoring this land and sea, but more on that in another blog.

What are Blue Akoya Pearls?

There was a question about natural Blue Akoya Pearls that came to the Cultured Pearl Association of America last week. I thought I would pass on this information because I have a  Blue Akoya Pearl and Aquaprase necklace in this email. The question was, how rare are they and what gives them their intense color? Natural Blue Akoyas are the rarest of Akoya Pearls.
“Natural Blue Akoya pearls can be incredibly beautiful and aren’t as rare as you might think. They have recently gained popularity…The color you see are not a result of a pigment. It’s organic matter on the nucleus. When a grafter improperly inserts a nucleus, it can cause a delay in the healing of the incision, resulting in inflammatory damage and abnormal secretions of organic matter, which appears blue through the nacre.” CPAA.
Sounds a little painful, but sometimes with beauty comes a little pain…

Pearl Qualities-Nacre

This drawing shows you a more detailed look at how nacre is formed. A mother of pearl shell bead nucleus is inserted into the host oyster, along with a square of donor mantle tissue from another oyster who has previously borne pearls of high or exceptional value, and the oyster is left to begin secreting around the nucleus, eventually forming a pearl.

The crystalline nacre layers are made up of microscopic aragonite platelets composed of calcium carbonate, and bound together with an organic “glue” of sorts called conchiolin. The aragonite platelets are fairly transparent to slightly tinged in color, able to both reflect and refract light rays striking their surfaces, giving pearls their trademark pearl lust and subtle glow. The tighter and more compact this arrangement of crystal is, the brighter the luster the pearl displays and the greater the amount of orient or iridescence.

Pearl Qualities-Color

Gold Lipped Oyster Shell

Yes. Let’s talk about color. I am sure you are aware, by now, that there are many colors of pearls in their natural state. But how do they get their color?

This is a Gold Lipped Oyster shell. What color pearl do you think this oyster made? Well, yes. Good guess. It is a Golden South Sea Pearl. The color of the pearl that an oyster creates is mostly determined by the interior color of the lip. The lip is the outer ring of the interior of the shell. Many pearl farmers will say that the mantle from a donor oyster used in the culturing process, determines the color about 80 percent of the time. The pearl’s nacre quality can affect its color as well. Others attribute environmental factors to determining pearl color – like the amount of salt in the water or the quality and quantity of food available to the oysters.

 The main color, or body color, is often modified by additional colors called overtones, which are typically pink (sometimes called rosé), green, purple, or blue. 

And, in addition to all of the colors of the South Sea and Tahitian saltwater Pearls, there are many natural colors of Freshwater Pearls. The intense colors of pinks, peaches, bronzes and lavenders can be mouth watering. But beware, Black Freshwater Pearls are not natural. They are irradiated or dyed. Best to stick with Tahitians for those dramatic darker colors.

There are so many choices of color in the pearl world. Find out which ones make your skin tingle.

Pinctada Maxima

Pearl Qualities-Surface

I had to dig deep to come up with these seriously flawed pearls. I usually through away any rogue pearls with problems, but these were stashed in some long forgotten bin. Thank heavens. These are ugly. 

Describing the surface quality of a pearl comes in terms of “flaws”. Most of the synonyms for flaws are: blemish, imperfection, irregularity, spot, surface characteristic, and surface mark or marking. But, which blemishes are acceptable and which are not?

These blemishes are not acceptable:

Cracks through the pearls surface. It is thin nacre that cracks, not thick. Thin nacre is the result of not spending enough time growing the pearl’s nacre.

Missing nacre. The pearl farmer has not taken care to grow the pearl with care and time. These are pearls that should not have even reached the market.

Discoloration throughout the pearl. It’s just not pretty.

Blemishes that cover the majority of the surface of the pearl.

It is normal for pearls to have some surface irregularity that gives them character and authenticity.

GIA, Gemological Institute of America, has established a 4 level system for grading pearls surface.

Clean-Pearls are blemish free or contain minute surface characteristics that are very difficult to see by the human eye.

Lightly Blemished-Pearls show minor surface irregularities when examined by a trained observer.

Moderately Blemished-Pearls show noticeable surface characteristics.

Heavily Blemished-Pearls show obvious surface irregularities that might affect durability.

Now you know.

Pearl Qualities-Luster (my personal favorite)

In this photo from the Gemological Institute of America, from top to bottom, these Japanese saltwater cultured pearls show excellent, very good, good, fair, and poor luster. The differences in the sharpness of the reflections between each adjacent strand are subtle but still noticeable.

Luster is one of the most significant pearl qualities. The luster of a pearl is much more than the luster of an object that is just reflective of the light on its surface. Luster refers to the light reflected off the internal layers of a pearl’s nacre. It’s a glow from within the pearl. The pearl’s layers of nacre is a translucent substance that is layered like bricks. Natural light travels through these layers and reflected back out in a prismatic lustrous rainbow in the best examples. The quality of the nacre is what creates the quality of the pearl’s luster.

Pearl Qualities-Matching

Matching is one of the Classic qualities of pearl judging. The perfect necklace would have all perfectly round, matching in every aspect, pearls. To make this necklace all of these pearls had to be the same round shape, the same color or tone of color, the same perfect surface condition, the same size…to the .15 millimeter, and the same level of AAA luster.

Pearl Qualities-Shape

I started in my last email illuminating on the first of the Pearl Qualities, Size.  This time we will talk about Shape.  Usually, the more round and symmetrical the shape, the more value the pearl will have. Round, Off Round or Potato Pearls, Drop, Baroque, and Circle Pearls are the run down in order of value for shapes of Pearls. There are some pearls with very distinctive shapes that are desirable.

Round pearls are actually very rare. The different shapes of pearls is caused by a number of factors in the growth of the pearl. Akoya and South Sea pearls are cultured by the insertion of a round nucleus into the gonad muscle of the oyster. Hence these pearls are already beginning with a round base. The shape also can be determined by where in the oyster the nucleus is placed. If it is too near the shell, it will develop with a flat side and that is a button pearl. Pressure on the shell can also cause the development of rings in the growth of a pearl and those are ringed or circle pearls. All irregular pearls are actually Baroque pearls, which means irregular. But within that definition, there are the classic Baroques with the fireball tail and also drop pearls. The most famous drop pearl is La Peregrina, a gorgeous natural drop pearl that has an elaborate history. Please check my previous blog about La Peregrina. Baroque pearls are not usually the most valuable, but because of their undulating surface, their luster can be a major positive asset.

Pearl Qualities-Size

Size dramatically affects the the price of pearls, especially above 7mm. People usually buy the largest pearls they can afford, but then again, it’s all about personal preference. Large pearls are rarer and usually require a longer time to mature. the largest pearls are from the South Seas and Tahitian waters. 

Pearls can range in size from 1mm to some of the largest at 20mm. 15mm to 20mm are very rare pearl sizes and maybe never seen in a fully matched necklace. There are several famous pearls that are larger, but that is another story. the size or weight of the pearl is the only grading factor that can be measured and can be related in exact figures.