Pearl Shapes and Grading

Doing research on one topic always seem to lead to about three other topics. While researching pearls, both as a buyer and a blogger, I happened upon a couple dozen topics.

Most recently, I ordered a necklace of akoya pearls from China. Now, like most buyers, I assumed my pearls would be perfectly round and have a glowing luster. But when I opened my package to view my new necklace, I was surprised to find a string of oddly shaped and grooved pearls. Now, for me, I loved the surprise. I wanted what I call “My Working Pearls” which means I'd have a pearl necklace I could casually wear while bringing a touch of elegance to my outfit.

Since I have these delightfully quirky pearls, I thought it might be nice to share some of my knowledge of pearl shapes, luster, quality, and lengths.

Pearls are graded into three categories:  A, AA, and AAA. AAA are upheld as the best, and usually most expensive, types of pearls. The different categories are decided by five factors, Shape, Lustre, Surface, Nacre, and Matching. The Matching usually only refers to pearl necklaces. The chart below gives a general diagram of the pearl grading works.

                        A                                 AA                              AAA  

Shape              Near Round                 Mostly Round             Round

Lustre             Fair                             Good                           High   

Surface           < 75% clean                > 75% clean                > 95%clean

Nacre              0.25/.35mm                 .35/0.5mm                   over 0.5mm

Matching        Fair                             Good                           Very Good

Shape

When most people think of a pearl, they imagine the perfectly round pearl but in truth these pearls are rare and very expensive. They are more common in cultured pearls than in natural pearls. This is because the longer a pearl stays in an oyster, the higher the chances of it becoming irregular.

Most pearls are actually termed 'off-round' which mean s they look round to the naked eye but they have flat surface spots or a slightly oval shape. Despite their irregular shape, these pearls are still of excellent quality in terms of luster and lack of blemishes.

Button pearls are round on one side and flat and the other side. This is achieved by clustering “seeds” (the term used for beads inserted into the oyster for culturing) in a row along the oyster's lip. These pearls retain their beautiful coloring and their flat edge makes them more manageable in earring posts or on rings.

Sometimes pearls form into an oblong shape, thus giving them the name 'oval pearls'. These oval pearls are also called 'rice pearls'. The name came to existence when China first started culturing their own pearls, their pearls weren't round but were oblong. These oval pearls were considered cheap in comparison to Japanese pearls and American thought the oval pearls looked a bit like Rice Krispies cereal, giving them the nickname 'rice pearls'. Sadly, oval pearls are still considered to be low quality, but I personally find them charming for cage pendents and in necklace and bracelet sets for young girls.

A blister pearl is a created when a forming pearl merges with the nacre of the oyster's lip. Some Buddhist cultures learned to make blister pearls in the image of the Buddha by inserting a lead figure into oysters and letting the nacre cover over the figurine to create Buddha pearls from these blister formations.

Baroque pearls, like the pearls in my necklace, are pearls that have tails or ridges (sometimes referred to as 'circles') along their surface. Baroque pearls are very common in the wild pearls and Tahitian pearls, due to the fact that both types of pearls take longer to grow inside the oyster. Baroque pearls are actually the highest percentage of pearl shapes despite popular belief that pearls are round.

Two other pearls shapes are 'keishi' and 'biwa', which were both coined by the Japanese. These pearls are accidental formations. In both, the oyster rejects the seeding method and forms its own jagged, stick like pearls. Biwa pearls are freshwater pearls from the Biwa Lake near Kyoto. Sadly, the production of pearls at Biwa Lake have ceased due to industrial pollution but the name lives on (incorrectly) for all misshapen freshwater pearls.

Lustre

Lustre, or luster, is how luminous or shiny your pearls are. Pearls of a higher quality tend to have an inner glow, a brilliance that is caused by the pearl reflecting light. A pearl with poor lustre will have a chalky surface or flat appearance under a light.

BEWARE BUYER – Some disreputable sellers will coat their lack luster pearls with lacquer to make them appear lustrous but these treatments are temporary and flake off over time.

Surface

To check surface quality, look at the shell of the pearls for dints, dents, bumps, bubbles, smudges, rough patches or irregular reflections. This is referred to as how 'clean' your pearls are.

Nacre

Nacre is measured under a microscope, usually by drilling into the pearl. Don't fear, these drill holes become your mount settings in the future. For the naked eye, judging nacre isn't really possible but some tips are to look for places where the pearl's surface seems thinner or thicker than the surrounding areas. (This is also a great way to check for flaking or faking).

Matching

Grading pearls for matching is usually meant for pearls that are in sets, like necklaces and bracelets. Individual pearls are usually not graded on matching.

Obviously, peals are not going to be identical, so matching is graded on how closely paired the pearls are in size, color, luster, and surface. The best way to determine matching is by placing your necklace on a light colored cloth background, under soft natural light. Avoid artificial light because it causes a false glare off of the pearls.

While examining your pearls, think to yourself:

•    “Are they all relatively the same size or are there noticeably smaller pearls squished in between bigger pearls?”   (Note: Some necklaces graduate in size for affect. Be sure to pay attention to patterns in the pearls, or a slow growth of small pearls to large.)

•    “Are my pearls of similar color?”

•    “Are they chalky, yellow, or dull?”

Overall the color, tone, and quality of your pearls should not be glaringly different but subtle and unnoticeable.

With a general observation of my new pearl necklace, I started to make a chart of my pearl's grading.

Shape:             A  (the shape of each pearl varies extremely)

Lustre:             A  (there are some very rough patches and blemishes on several pearls)

Surface:           A  (see above)

Nacre:              A  (my nacre is thin in some places)

Matching:        A  (none of my pearls match each other but their color is very similar)

My pearls are of Grade A quality, but I find them generally wonderful.