Red Pearl Line

Freshwater pearls are grown in freshwater molluscs (mussels), while Akoya,Tahitian and South Sea pearls (saltwater pearls) are grown in oysters. 

The catalyst inserted to the mollusc is just a very tiny piece of an oyster's mantle tissue instead of shell beads (which guides the shape in saltwater pearls, e.g. round pearls). To reduce and resist this irritation  from this foreign material, the mollusc coats the "intruder" with the same secretion it uses for shell-building, nacre.

In a mollusc this nucleating may be completed 25 times on either side of the mantle, producing up to 50 pearls at a time while in the oyster it can only be done once or twice producing 1 or 2 pearls. (Hence the price difference between freshwater and saltwater pearls).

The molluscs are then returned to their freshwater environment where they are tended for 2-6 years. The resulting pearls are of solid nacre.  However, without a bead nucleus to guide the growth process, the pearls are rarely round.

Nevertheless, in recent years the Chinese have been able to take the art of culturing freshwater pearls to new levels and have produced remarkable round freshwater pearls.

In the last decade the quality of pearls produced have become so high that many pearls in the top percentage of a harvest are almost indistinguishable from their saltwater relatives. In other words, rice-shaped seed pearls  are now being replaced with round, lustrous pearls of sizes as large as 16mm, mimicking large South Sea pearls.

This has created a renewed interest in freshwater pearls as an affordable alternative to the much higher priced saltwater pearls.

Pearl Grading System 

Pearl grading is very similar to the 4C's of diamond grading in that it takes into consideration several categories of qualitative comparisons. The pearl grading system consists of five main parts:

• 1. Lustre
• 2. Shape
• 3. Colour
• 4. Surface
• 5. Size

Although size will certainly play an important roll in evaluating the price of a pearl, lustre, shape, colour and surface quality are of primary importance.

Two major grading systems are in fairly widespread use: the 'AAA-A Grading System' and the 'A-D Grading System' - also called the Tahitian grading system. These are the most universally accepted standardized systems, and are used by nearly all reputable retail and wholesale pearl dealers.

The AAA-A Pearl Grading System - Freshwater and Akoya

This system grades pearls on a scale from AAA to A, with AAA being the highest grade, this grading scale is common to freshwater and akoya pearls only, but is accepted by many South Sea and Tahitian pearl dealers. The AAA to A grades are as follows:

AA: The surface will have a very high lustre, and at least 75% of the surface will be free from any type of defect.

A: The lowest jewellery-grade pearl, with low surface lustre and/or more than 25% of the  surface showing defects.

The A-D Pearl Grading System - Tahitian and South Sea Pearls

This grading system grades pearls on a scale from A to D, with A being the highest grade. This system is used in French Polynesia to grade Tahitian and South Sea pearls only.

• A: Highest-quality pearl, very high lustre and only minor imperfections over less than 10% of its surface.
• B: High or medium lustre. Surface may have some visible imperfections over no more than 30% of its surface area.
• C: Medium lustre with surface defects over not more than 60% of the surface area.
• D: May have many slight defects over 60% of surface or deep defects over no more than 60% of surface.

Pearls of the "D" variety may have a combination of minor and deep defects over no more than 60% of its surface. In this grade of pearl, the lustre is irrelevant. Even the most lustrous pearls will be graded D if their surface areas is blemished to this extent.

Pearls below D grade are considered not acceptable for use in jewellery.

Both of these grading systems focus primarily on the lustre and surface quality of the pearl to determine its grade. There are however, other factors that contribute to the quality and value such as thickness of nacre, especially in saltwater pearls.