PEARL EDUCATION
Pearls are formed as part of an immune response inside the shells of certain mollusks. The process is part of a defensive mechanism against parasites or other threats that could injure the creature's tissue. I tiny piece of tissue begins the formation of a pearl sac into which the tissue deposits calcium carbonate. Pearls are considered feminine and are associated with the moon and the planet Venus.
Size
Pearls are typically measured by their diameter in millimeters rather than by weight. The larger the pearl, the higher the price, though price steps can be inconsistent. Once a pearl reaches 8-9mm in diameter, the prices tend to increase much quicker than at smaller diameter ranges.
Shape
Pearls are often round or ovular. Pear-shaped or misshapen pearls are called "baroque pearls." Symmetrical spheres or symmetrical drops are the most valuable shapes. They typically range between 2 mm and 16 mm in diameter, but the size depends on the type of mollusk that hosts them.
Clarity
High quality in terms of clarity means the pearl's surface has the characteristic "pearly" luster and creates sharp and bright reflections on the surface. A good one will be smooth and blemish-free with a layer of nacre to improve durability.
Color
Pearls come in various colors from white to black. The natural color is influenced not only by the color of the basic pearl material but also the overtilling and interplay of lustrous surface materials. In some cases, that can create subtle color combinations, producing pink, green, blue, or even silver. The color will often shift and shimmer as you move it about in your hand.