About Black Pearls - Classification
When harvesting pearls, the farmer performs an initial sort of-this crop, discarding all the rejects. He then performs a more detailed separation of his crop sorting out pearls by size, shape and quality.
Size
Pearls are most commonly measured in millimeters.
Shape
There are four basic shapes that Black cultured pearls come in:
Round and Semi Round
Round pearls are almost-perfect spheres whose diameter variation rate is less than 2 %. Semi round pearls are slightly imperfect
spheres whose diameter variation rate is greater than 2 % but less than 5 %.
Semi-Baroque
Semi-baroque exhibits at least one axis of rotation and are subdivided into drop, button, and oval shapes.
Baroque
Baroque pearls do not have any axis of rotation and are asymmetrical in shape.
Circled
Circled or ringed pearls are characterized by regular streaks or concave rings, perpendicular to an axis of rotation over
more than one third of the pearl's surface.