PG Editor

By C. Denis George Abstract by Anna Kerrig

Historical Aspects on the Early Discovery of the Pearl Cultivating Technique

Japanese scientists, Nishikawa and Mise are typically recognized for discovering the technology that led to cultivating spherical pearls. C. Denis George was an Australian enthusiast who challenged the credit given to the Japanese for this discovery. George argues that Nishikawa and Mise's step-father were first exposed to successful pearl cultivation at Thursday Island...

Measuring Pearl Quality
Pearl quality and thus, the value of a pearl is measured according to a combination of several varied factors are: the type of pearl, the thickness of its nacre, its luster, the cleanliness and texture of its surface, its shape, its color, and its size.


Because the pearl is a naturally occurring organic gemstone, created by living creatures, these factors can and do vary widely. Although all of them affect the ultimate value of a given pearl, some of the factors are...

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 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...