Pearl Education

Pearl Nucleus Defined
A pearl nucleus is a bead or other object implanted into the gonad of a marine mollusk or into an existing pearl sac in the gonad or mantle of a freshwater mussel around which nacre deposition occurs.

The Pearl Nucleus and Nucleation/Grafting
Pearl farms vary depending on the type of mollusks being produced. But the one thing all pearl farms share is the process of nucleating the mollusks to produce a pearl. Every cultured pearl produced commercially today, except for...

Pearl-Producing Mollusks (Pearl-Producing Bivalves)
Mollusks represent one of the world's earliest forms of animal life, and date back over 550 million years. Actual pearl-producing mollusks first appeared 530 million years ago, when mollusks developed shells. The scientific discoveries of pearl producing mollusks illustrate the intrinsic and irrefutable value of the world's most historically treasured organic gem.

(A fossilized shell of an Abalone from Baja California, Mexico, photo...

Pearl Size Is Measured in Millimeters

A pearl's size is measured according to its diameter in millimeters. Sizes range from 1 millimeter or less, in the case of very tiny pearls, to as much as 20 millimeters (more than 3/4") for large South Sea pearls.

The Average Pearl Size Today is 7.0-8.0 Millimeters

Most white pearl strands sold today fall in the 7.0 to 8.0 millimeter range. This is considered a classic, conservative size.


A 6 mm and a 12 mm pearl

The Larger the Pearl Size, the...

Pearl Shapes Vary Widely
Because pearls are natural organic gems created by a myriad of living organisms, they occur in a wide variety of shapes, many of which are quite unique and interesting. Also, cultured pearls tend to be rounder than natural pearls because (saltwater) cultured pearls usually have a bead inside that will help guide the shape.

Some shapes are distinctively unique to certain species of mollusks, as is the case in Abalones (Haliotis spp) that commonly produce conical or...

Pearl Surface in Pearl Grading
The surface cleanliness of a cultured or natural pearl has a direct correlation to its value. A pearl can never, according to rules set forth by the FTC, be graded as "flawless", but the degree or percentage of inclusions or surface imperfections can be measured by anyone with experience.

What to Look for on a Pearl's Surface

When grading pearls, the appearance of the surface of a pearl is one of the most important characteristics in determining its overall...

Pearl Treatments Defined
Pearl treatments are defined as any action other than polishing which alters a pearl's appearance which may include:

irradiation
bleaching
heating
filling
waxing
drilling
cutting
faceting and
working

Pearl Treatments just after Harvesting

After harvest, most pearls are always processed in one way or another. This processing may be subtle or less so.
South Seas, Tahitians and Cortez pearls are usually just washed and will undergo minor tumbling with waxed bamboo...