Pearls are classified by origin, then graded by size, shape, nacre thickness, color, luster, and surface clarity. These qualities are not considered to be of equal importance. Some factors will be weighted to give them more influence in arriving at a final grade. When considering a purchase of pearls, be familiar with the information below and ask your retailer how these attributes apply to the pearl type you are considering.
- Luster – For cultured pearl experts, luster is perhaps the most important indicator in evaluating cultured pearl quality. Luster is what separates the superior from the inferior and the extraordinary from the ordinary. Luster is what many experts term the heart and soul of the sea-grown gem. Throughout history, this unique attribute has separated pearls from all other gems.
- Surface – Surface quality refers specifically to the abundance or absence of physical blemishes or marks. When evaluating surface (the trade uses such terms as blemish, spotting and cleanliness), remember that cultured pearls are grown by live oysters in a natural environment. As such, there are many uncontrollable forces that affect the surface.
- Shape – Shapes range in descending order of value from round to semi-round, from off round to oval and from drop to baroque. It’s important to understand that in pearl industry terms, generally the shapes from round to drop are pretty symmetrical, while anything baroque denotes a pearl that is completely asymmetrical or free-form. The aforementioned shapes usually occur in Japanese Akoya cultured pearls as well as Tahitian, South Sea and Freshwater pearls.
- Size – Cultured pearls are measured by their diameter in millimeters. They can be smaller than one millimeter in the case of tiny seed pearls, or as large as twenty millimeters for a mature South Sea pearl. The larger the pearl, other factors being equal, the more valuable it will be.
- Color – Cultured pearls come in a variety of colors from rosé to black. While the color of a pearl is really a matter of the wearer’s preference, usually rosé or silver/white pearls tend to look best on fair skins while cream and gold toned pearls are flattering to darker complexions.
- Matching – Refers to pearl selection for pairs or strands, and addresses uniformity of color, luster, shape, spotting and graduation. If colors are intentionally mixed, it refers to the attractiveness of the combination. Even in “uniform” strands, there will be graduation in size from the center pearl to those at the ends. Each pearl in a strand has been selected to be placed between its neighbors on each side. There should be no significant difference between pearls that are side-by-side.