Pearls are the only gemstones to be natural, they are the organic products of living creatures, and they have different grading standards.
Netpearls.co.uk uses the most common pearl grading system: A, AA, AA+, e AAA. This ranking is the one you find in all products of our catalogs. Six factors determine the quality, value and beauty of pearls: nacre, luster, surface, shape, color and size. We hope this guide will be helpful for you making your choice in purchasing cultured pearls.
The first step is to identify the type of pearl; Freshwater pearls, Akoya pearls, Tahitian pearls or South Sea pearls, the four main pearl types used in jewelry. Each type of pearl is produced by a different pearl oyster, and each mollusk lives in a different region of the world under very specific climatic conditions.
Nacre is the natural substance that the mollusk secretes to protect itself from irritants such as shell fragments, parasites or implanted beads. This is the same beautiful iridescent material that we can observe in the inner surface of the mollusk shell, aptly named mother of pearl. Nacre thickness is a quality factor only applied to saltwater, bead-nucleated pearls. It is not applied to Keshi pearls or Freshwater pearls as both are composed of solid nacre.
Luster is the measure of quantity and quality of light that is reflected from the surface, or just under the surface of a pearl. The luster of good quality pearls is sharp and bright. You should be able to see your reflection clearly on the surface of a pearl. Any pearl that appears too white, dull or chalky, is of low quality.
The cleaner the surface of the pearl, the more valuable it is. Look for an absence of disfiguring spots, bumps or cracks on the surface of a pearl, also known as "cleanliness." Notice that the highest quality pearls have a sharp, mirror-like reflection.
A perfectly round pearl is very rare. The rounder the pearl, the more valuable it is. Baroque pearls are not symmetrical in shape, and can be lustrous and appealing, but will typically cost less than round pearls.
Pearls come in a variety of colors, from white to black and every shade in between, even if they are never really black. It is important to distinguish between color and overtone. For example, some naturally occurring colors are white, champagne, green, golden, and black. Within each color category, there are a number of common overtones, or subtle variations in the surface iridescence.
When all other value attributes are identical, the value of a pearl is determined by its size. The larger the pearl the more valuable. Pearls are measured by their diameter in millimeters. If all other quality factors are equal, the value of a pearls id determined by its size. Only a 1 millimeter increase in pearl size is a substantial jump in both appearance and value. The average pearl sold today is between 7 mm and 8 mm.