Since freshwater pearls are tissue nucleated . . .
Some freshwater pearls are tissue-nucleated; others are
bead-nucleated. In fact the subject of fresh-water pearl nucleation
has been hotly debated of late, since the Chinese are growing such
large, round pearls and claiming they are tissue-nucleated, which
some experts believe to be impossible. These experts say that what
makes a round pearl round is the shape of the bead that’s inserted
and around which the oyster deposits nacre. In fact, some of the
Chinese fresh water pearls have been found to be nucleated with other
pearls – presumably imperfect/low value ones that have been ground
down – rather than with shell beads. These pearl-nucleated pearls,
since they are composed of all nacre, appear to have no nuclei.
Other examples when examined, however, do seem to have no perceptible
nucleus. The conclusion seems to be that pearl manufacturers will
use any and every method at hand to produce a high luster, large
round pearl as quickly as possible.
Saltwater pearls being bead nucleated will seldom have [growth
rings], as the nacrous coating is thin over the perfectly round
There are plenty of salt-water circle pearls around! I see them all
the time – in black Tahitians, for instance. As for the nacreous
coating of a salt water pearl, yes it would be thinner than the nacre
of a tissue-nucleated pearl but patently not too thin to produce