Tag Archives: pearl education

A

AAA Grading system

Pearls are usually graded between A and AAA, with A being not very good to AAA which should be of the specific shape (usually used for round pearls) smooth surfaced (with only very small and near invisible flaws) and of high shine or lustre

AA+ Nearly as good as AAA but perhaps slightly off round when rolled and a few more flaws although these will still only be visible on close inspection. Look closely below- the halos are slightly oval because the pearls are off-round although the halos are still pretty regular

AA Average to good lustre, off round, blemishing to 20% of surface

A: This is the lowest jewellery-grade pearl, with a lower lustre and/or more than 25% of the surface showing defects. Probably a ’round’ pearl will be egg shaped, even from a distance

The problem with this system is, of course, that you may be faced with a smooth surfaced and metallic pearl which is off round to the point where it drops from AAA to AA+ or even AA. It will still be a beautiful pearl and one which will probably look round when worn but many buyers will be deterred by an AA grading.The lustre reflection below differs noticeably between pearls in terms of reflection and shape and the one to the left of centre has a grooved surface flaw’

A+ Low quality. Visibly off round and very variable lustre. Many flaws in the surface

(any website or other seller which talks about AAAA+++ grade pearls is talking rubbish and this should be challenged).

Tahitian pearls have a distinct and separate system, established by GIE Perles de Tahiti, and the Ministere de la Perliculture of Tahiti which grades from A (finest) to D ( poor) but to avoid confusion Pearlescence uses only the A-AAA gradings throughout the website.

We also have adopted the name ‘Essence’ for pearls which are exceptional. They have been selected for highly metallic lustre, clean surface and shape, in that order. Usually only found by selecting in person. Probably under 1% of pearls will show the mirror metallic lustre we look for

Abalone Pearls

Research and new farming for abalone pearls has started in New Zealand in the last few years..

  The abalone produces a distinctive and    tunningly iridescent blue pearl but is very hard to nucleate as its blood does not clot, so any damage will kill it.There are natural (wild) abalone pearls out there, with wildly baroque shapes and a distinctive horn shape tapering from a broad and sometimes distorted and ugly base to a sharp tip

Akoya

Akoya pearls come from the akoya oyster (Pinctada Fucata Martensii), which is the smallest pearl producing oyster (6cm to 8cm). This is why akoya pearls over 10mm are very rare while the normal size is about 6mm to 7mm It is a salt water mollusc.

Little akoya pearl oyster

Most cultured sea pearls are akoya pearls which are made with a bead nucleus, so that they usually have a good round shape. Big irregularities tend to be tails while less than perfect pearls have nacre with pits or convolutions. Good akoya pearls have a sharply reflective metallic lustre. Most akoya pearls come from Japan with a small production in China.

Akoya oysters like to live in water one to five metres deep and in temperatures of between 15 to 24 degrees Celsius

Modern pearl farming began properly in 1905 when Kokichi Mikimoto produced the first round farmed pearls. The company which still bears his name continues to be a world leader in the provision of the finest akoya pearls

Akoya pearls are harvested after only 9-16 months. The main thing to be aware of is that akoya pearls which are too cheap can have only the thinnest layer of nacre. Pearls with very thin nacre may even ‘blink’ which means that when rolled the nacre blinks to show patches where there is no nacre and you can see the nucleus. Below is a very bad example – the cream colour is nacre and the white is nucleus. Even when the nacre appears solid it can be very thin: peer closely and you can just about make out the thin line of the black nacre on the akoya pearl on the left (which split in half) The nacre on the pearl on the right is so thin the pearl is a ‘blinker’ .


Very thin black nacre Nacre so thin the bead is visible in places


You can see the thin akoya nacre

in these split pearls



Recently the trend for natural colour pearls has spread to akoya pearls and where once

Blue single vietnamese akoya pearl grey blue round akoya strand

every akoya pearl would have been bleached to make it white (and then often pinked to give a pink overtone) now akoya are available in delicate natural shades of pink, grey, or gold as well as a dark grey/blue which also has strong green highlights

Most white akoya are bleached, though some natural white are available. Black akoya are dyed and can look too uniform and dense in colour, while it is also hard to find gold akoya which haven’t been dyed. Suspect strong gold tones and opt for delicate blush tones



Natural pale gold akoya pearls. Natural mixed colour akoyas

G

Gamma Radiation

Gamma irradiation turns the nacre of freshwater pearls very dark, and often also imbues a metallic lustre with rainbow orient. Strangely, it has no effect on salt water nacre but will turn the nucleus dark which shows through the layer of nacre, making the pearl look grey or blueish There is no danger of radiation contamination from irradiated pearls.

Granulated

or popcorn pearls have a knobbly surface which resembles..popcorn. This granulation is often mixed with patches of high lustre surface. When the Chinese freshwater pearl business was starting up most of the pearls were, at least to some degree, popcornish and oval in shape. Term also used for the earliest Chinese freshwater pearls which were called Rice Krispie pearls.



Loose, undrilled white rosebud /granulated pearls

Gold Leaf Pearls

This is the name we give to the extremely beautiful lustrous gold pearls which are natural pearls with a layer of aragonite with an incredible lustre – so it does indeed look as if a layer of gold leaf has been applied to the pearls.


These pearls show the stunning gold colour which

looks as if gold leaf had been applied to the pearl surface

Gold-lip Oyster

A large oyster (variety of Pinctada maxima) used in some countries to produce South Sea cultured pearls; it produces a yellowi nacre, and pearls that typically range from off-white to rich, deep gold in colour.


Loose undrilled gold south sea pearls waiting to be paired for earrings

Goniochromism

An optical phenomenon which causes the hue of the pearl to change colours depending upon the angle from which the pearl is viewe. Popularly called colour-change pearls

T

Tahitian Pearls

are produced by the black-lipped oyster (Pinctada margaritifera). They have been produced for almost exactly 50 years now in French Polynesia, in the lagoons of remote coral atolls and islands – everywhere except on Tahiti Itself!


Kamoka pearl farm,. Ahe atoll, French Polynesia

Black Lip Oysters are now also being farmed in a small way in Australia. The oyster itself is quite large — sometimes up to 12 inches across and weighing as much as 10 pounds — which often results in much larger-than-average pearls. The pearls are unique because of their natural dark colours. Most “black” Tahitian pearls are not actually black, but are instead grey, silver, charcoal,chocolate brown, blue, purple, aubergine, pink, beige or even off-white Truly black pearls are extremely rare.


Black pearls….

Tahitian pearls are grown around a bead so are often round but can be semi round to drops as well. Circles are common, and some prefer circle pearls because they are clearly real and not imitation. Tahitian pearls go through x-ray inspection before legal export (ask to see their export certificate and confuse most jewellers!) and have a different grading system A-D where A grade are the best pearls

Third graft

Sometimes molluscs yield pearls of such quality that farmers put them back in the water for a third time. Third graft pearls will be very large indeed, and the mollusc could be ten years old.

Top drilled

Asymmetrically drilled pearls, often oval. If strung un-knotted they tend to move around against each other on the silk and then are called dancing pearls