The shine or luster of a pearl is measured by how well the pearl’s surface reflects light. A high-luster pearl will have a glowing mirror like shine, with sharp and bright details in the reflection. Lower-quality lusters will have either a chalky or dull surface, which is typically accompanied by blemishes.
Genuine pearls will have organic spots, marks, or indentations on the surface. The surface clarity or cleanliness of a pearl is evaluated based on the size, number, location, and visibility of these natural imperfections. The smoother and more blemish-free the surface of the pearl, the higher the value.
The symmetry of the shape of a pearl is a key factor in determining the value of a pearl. While pearls come in a variety of shapes, the rarest and highest-quality are perfectly round. Lower quality pearls are often elongated, this off-round shape is commonly referred to as potato-shaped.
While a pearl’s size does not affect the quality or grading, it does have a significant impact the price. Because large pearls are more difficult to cultivate, they are more rare, and as a result- more expensive. All pearls are measured in millimeters (mm), often ranging in either whole sizes or in diameter increments.
Matching refers to the uniformity of pearls in a jewelry piece and depends of the consistency of color, luster, surface, shape and size. While no two pearls are ever identical and slight variations are to be expected, expert pearl stringers hand-select and match pearls in a specific order to ensure a smooth blend.