Fireball Pearl
A freshwater pearl with a comet-like tail, formed when the mussel partly rejects the bead.
A fireball starts as a bead-nucleated pearl. When the mussel pushes against the bead, nacre builds up on one side into a distinct tail.
The result is a rounded head with a flared tail, usually with strong metallic lustre.
No two are alike, and they are used where a single dramatic pearl carries the whole design.
Souffle Pearl
A large hollow freshwater pearl, grown around mud that is later washed out. Very big and very light.
Baroque
Any pearl with no axis of symmetry. Once treated as a reject, now the shape most associated with contemporary pearl design.
Bead Nucleated
Grown around a round shell bead, so the pearl is a nacre shell over a core. The saltwater method, and how roundness is achieved.
Lustre
How sharply a pearl reflects light. The single most important quality factor, and the one you can judge without any training.