Circled Pearl
A pearl with grooves or rings running around it. Traditionally a defect, now often sold as a feature.
Circles form as concentric bands around the pearl's axis, thought to result from rotation during growth.
In grading terms they are a surface fault, and a circled Tahitian or South Sea pearl costs substantially less than a smooth one of the same size.
Designers use them deliberately, because the banding catches light in a way a smooth pearl does not.
When you are buying
The most economical route into a large Tahitian or South Sea pearl. You give up a grading point that many people find attractive anyway.
Surface Blemish
Pits, bumps, creases and dull patches on a pearl's surface. Some marking is present on essentially every pearl.
Baroque
Any pearl with no axis of symmetry. Once treated as a reject, now the shape most associated with contemporary pearl design.
Tahitian Pearl
A naturally dark saltwater pearl from the black-lipped oyster of French Polynesia. Grey to near-black, with green, aubergine or peacock overtones.
Pearl Grading
The A to AAA scale used to rate a pearl on lustre, surface, shape, colour matching and nacre. There is no global standards body enforcing it.