Mabe’ pearls are almost always glued constructions. The blister
is grown normally in the oyster, over a half dome of either
plastic or cut from mother of pearl. I’ve seen both. After it’s
cut from the parent shell though, is sometimes needs to be
reassembled. Sometimes not. The back half is always an
addition, and you can always see the seam between front and
back. In a few cases I’ve seen these where the hollow nacre dome
has a bead, not a hemisphere, filling most of the bulk, with the
substantial remaining volume just filled with plastic or epoxy or
maybe even duco cement. Wasn’t sure what it was. Made a mess
when it came apart. You’ll find many of the solid blister
pearls are also similar, with a plastic dome under the nacre
surface, except that in those, it’s the original dome the pearl
was grown on with no subsequent addition of a seperate back.
The difference in quality between good and not so good mabe’s
does not depend on this filled construction, since they can all
be considered to be such constructions. Instead, like all
pearls, the real quality factor is the thickness of the nacre
layer (Plus, of course, flaws, color, orient, etc.) Good ones
will have the nacre blister a good 3/4 of a millimeter or more,
and these will hold up fairly well. Some, though, are almost
paper thin. It can be a real problem determining the good from
the bad, since the construction hides the edge of the nacre which
would allow you to see the thickness.
One unpredictable problem with mabes that have not had the
filling reassembled after being cut from the shell (most of them)
is that you then don’t always know how well the layer is
attached. Occasionally, one will just pop off as you describe.
But in my experience, as often as not, it’s the fault of the way
the pearl has been treated. Too much pressure while setting a
bezel, for example. Or the use of a harsh blast of steam directly
under the nozzle. Or solvents of some sort, such as in cleaning
off excess epoxy after gluing. That sort of thing, if it seeps
between the nacre blister and the filling, can easily seperate
the pearl. It’s happened to many of us now and then. if the
seperation did not damage the surface of the filling (many of
them are coated with a sort of reflective layer, which does
show through the pearl layer, increasing whiteness) you can often
just epoxy the pearl blister back onto the filling without too
much change in appearance. Be very careful to get an even,
bubble free layer of epoxy as thin as possible. A little tricky
to do, but sometimes works. If that irridescent coating on the
filler has been damaged, that area will often appear as a shadow
in the mabe after it’s reglued together, but even then, sometimes
its acceptable as a repair if you cannot replace the pearl for
some reason. And of course, if the nacre has been actually
cracked/damaged or punched through, the pearl is likely dead.
Whether you can request replacement of the pearl from your dealer
depends on the pearl and the dealer. If it was really costly and
represented as highest quality, and that nacre bubble is only .2
mm thick, you’ve got a valid gripe. If this came apart after the
customer spent all day with her hands in paint solvent while
repainting the garage, then I’d have to say the pearl only did
what it was gonna do with that treatment.
Hope this helps.
Peter Rowe