Working with South Sea's Pearls

Jewelry Discussion
1

I have a recently received a South Seas pearl oyster shell (about
the size of a man’s hand) with a “half” pearl (~1/2" is diameter,
absolutely gorgeous silver grey iridescence too)) embedded in the
lip. Not having worked with pearl shell (or pearls of this calibre)
before I’m slightly uneasy about just cutting into it to liberate the
pearl, but I “can see” a pendant with this beauty in it and really
would like to make a start on this. BTW I can probably get some more
from the same source as she just likes to see them being appreciated,
the two she gave away to friends on the return from her travels have
disappeared into various brick-a-brack draws or what ever and have
not been seen for 18+ years, this hasn’t made her very happy.

So where/how do I start? I would imagine getting my hands on a book
or two will be a good start, so any suggestions on this front?

The other thing I’d like to try to establish is a ballpark value
figure for this pearl, so here is what I know…

The shell was collected (along with about 20 others) in the vicinity
of Tahiti about 20 years ago, they were not purchased, but collected
either from the sea floor or beaches (this one has some scratches
that indicate that the oyster was removed from the shell with a sharp
implement) at the time the collector was told they were worthless and
to dump them over board (thankfully she didn’t!!!). I’m almost
certain that they have not been artificially seeded (would
artificially seeded oysters be “running” free on the seafloor?), the
dome isn’t quite round, nor is it half as high as it is round, so it
is kind of a low dome shape about 5.5mm high and 14.71mm in diameter.
The colour transitions from a black grey on the lip “side” to a
sepia-grey on the oyster side, the iridescence is very uniform and
rather intense with hints of blues and greens and quite a bit of
peacock blue as well.

So with out a picture (I will post one within 24hrs) what would be
good guestimate for this little treasure of the sea?

Cheers, Thomas.
Janstrom Designs.

2 
I have a recently received a South Seas pearl oyster shell (about
the size of a man's hand) with a "half" pearl (~1/2" is diameter,
absolutely gorgeous silver grey iridescence too)

Thomas, working with it is pretty simple. Assuming you don’t have a
lapidary outfit… You can cut nacre, which is what all shells
and pearls essentially are, with a hacksaw - a wet diamond saw is
best, but a hacksaw (or coping saw) will do. Everything you do will
generate lots of dust, BTW - bad dust, but not toxic (poisonous).
Again, a wet lapidary wheel is best, partly to keep the dust down,
but you can grind it with a large (like 4"-6") Cratex wheel or a
belt sander. You’ll soon see why I keep mentioning dust - there’ll be
a lot of it. Mother of pearl, which is a shell, takes a fine polish,
but pearls are not polished, they have a natural luster. which is to
say that if you touch the mabe’ itself with any of your tools it
will become garbage. You can polish it but it won’t be a pearl, it
will be polished mother of pearl. It works very much like a hard
plastic. As for value, I really can’t say. I know natural (undyed)
cultured south-sea mabe’s are into a couple of hundred dollars or so,
depending. If yours is hollow, you’ll need to fill it, too. Many
mabe’s are a shell with a MOP back and resin inside to support it.

3

What you have sounds just like a sample of oyster shell with a human
started mobe pearl in it that I own. It is extremely unlikely that
the pearl part is natural. If you cut into the shell from the back
side of where the pearl is, I’m pretty certain you’ll see the
starter piece inside. I don’t think they have a lot of value except
as display pieces (that’s what I use mine as).

Daniel R. Spirer, G.G.
Daniel R. Spirer Jewelers, LLC
1780 Massachusetts Ave.
Cambridge, MA 02140

4

G’day Thomas

I have been searching for such a set of shells - but I want a set to
recreat a pre-raphaelite painting called “the water Baby” - I have
the porcelain baby but lack the shell. And your friend can be
reassured that it (or they ) would be absolutely treasured. If I can
get two sets even better - one for my dressing table for the oddments
of jewellery I take off at night or to do the dishes.

Thanks
sue

5

Hi Daniel,

It may be that for you, but to me it’s a beautiful pearl and mother
of pearl shell. A lot of the stones I work with are not all that
expensive to buy loose or as rough, but when used in a finished piece
of jewellery it’s a whole nother story, so even if this mabe pearl is
only worth a few bucks, when I set it in 18K palladium white gold
with some accent diamonds etc. (as an example) well I’m sure you get
the idea.

On the make up of it, I know the provenance of this shell in quite
some detail, and if I (or you) need more info I’m sure I could even
get you the lagoon/reef from which it was collected. To be honest I
don’t actually care all that much if it’s cultured or not (see above
for reasoning) I just really want to do the “stone” justice when I
come to set it, as I do with every stone I have ever set.

Cheers, Thomas.
Janstrom Designs.

PS. Please don’t take this the wrong way, I just can’t think of any
better words to use in the above, I’m not angry or offended by your
comments in the least, it’s all to me, which I asked for,
so I thank you!

6

Hi John,

That’s the sort of info I’m after, I don’t personally have the
required tools but I do have access to them so I should be able do
this the right way. I did read online that the dust is a problem (can
cause dust related disorders/disease) not onle from a health stand
point, but just because so much is created. It reminds me of working
with graphite (AKA compressed filth) on machine tools!

I guess real care is called for, I might leave this project for a
bit and do some general shell carving to get some practice working
with shell and power tools.

If you or anyone else wants to see some pics the link is:

Thank you.

Cheers, Thomas.
Janstrom Designs.

7 
did read online that the dust is a problem (can cause dust related
disorders/disease) not onle from a health stand point, but just
because so much is created.

The proper name for oyster producing South Sea pearls is Pinctata
Margaratifira. It is a large animal and filters a lot of water,
concentrating heavy metal pollution. There could be very profound
health effect.

Leonid Surpin.

8

Thomas-- You can take a jewelers saw and saw around the pearl,
either close to the pearl following it’s shape or as a more free form
object. Please keep in mind that working with MOP can be dangerous–
the pearl dust is toxic, on a par with silica or other mineral dusts
in that it accumulates in lung tissue.

This “pearl” could be one of several things. Without seeing your
picture, sounds like what is known technically as a “blister”
pearl-- normally, what you see is what you get, there is nothing
inside to liberate.

If it’s a perfectly round hemisphere or other regular shape such as
a heart or drop, it’s probably a “Mabe” type blister, where a manmade
nucleus, usually a hemisphere of plastic or other material, is
cemented to the shell and subsequently coated with nacre by the
mantle tissue of the host mollusc. Your description of the
circumstances suggests Mabe-- usually $200 - $400 retail (3K)

Here you should be careful if you cut close to the pearl because the
MOP shell layers can separate off leaving an thin “eggshell” of
nacre and the nucleus which could be anything from plastic to
soapstone. The nacre doesn’t really attach to the nucleus so the
nucleus can pop out.

“Blister” pearls are also created by cementing a MOP shell bead to
the living shell, so the mollusc coats the bead with nacre much like
a typical saltwater bead nucleated cultured pearl, i.e. Akoya, South
Sea, or Tahiti. In this case, the nacre attaches to the bead much
more firmly and the nucleus is an integral part of the pearl, so you
can trim the shell however you like-- some times these are made into
3/4 pearls with a flat spot on the bottom.

Natural blister pearls are caused where various natural actions like
parasitic invasions or pieces of shell debris become the nucleating
agent. These would characteristically be irregular in shape.

Rarely, a pearl (within the body of the mollusc) will get so big, it
can break thru the mantle tissue and settle against the shell. The
mantle will repair the break and the natural nacre secreting action
will continue and begin to form a “blister”. Old time AMFW pearlers
would look for “crippled” shells-- the blister would cause irregular
shell growth. This was a case where a true natural pearl could be
“liberated” – this required a “Pearl Doctor” who knew the difficult
technique known as “peeling” – truly a lost art these days.

Jim
Mardon Jewelers
www.mardonjewelers.com

9

Hi Jim,

Thanks for the info, it filled a couple of blanks in what I have
found so far. Still a ways to go, but I’m not quite ready to start
cutting the shell just yet, I now have about a dozen sketches (some I
will use with other stone(s)) and I’m still not really happy!

Going on what I have found out to date I’m thinking it might be a
seeded mabe pearl, it’s quite round (only about 0.5mm discrepancy),
but a bit shallow to be hemispherical (5.5mm vs. 7.3mm it should be).
I know it comes from around Tahiti somewhere (I haven’t asked exactly
where), but the distribution of the oyster in question is rather wide
spread in that part of the world, so it could be anyone of 500 or so
atolls, islands or reefs! I won’t rule out it being natural, but
going on the shape I’m starting to think it’s a long shot, not to
worry, it’s still as pretty today as it was last week!

Incidentally there is a shallow oval blister pearl of to one side of
the big one, it’s only 2mm high by 6mm wide and 18mm long, so this
one might be natural (it’s rather irregular in shape), but isn’t
quite a pretty, not as much colour and the lustre isn’t the same…
Still it has it’s charms, one of the big ones is it’s there!

When I do start to cut out the pearl I will be wearing a half face
respirator, you only get one set of lungs (normally) and it pays to
keep them in good nick.

Cheers, Thomas.
Janstrom Designs.

10

I’ve worked on many mabe pearl rings and earrings where I’ve had to
soak the pearl out of the mounting. Every one I’ve come across is
made with the top blister of nacre, a round mother of pearl ball
inside with glue filling up all the empty space, and a flat mother
of pearl backing piece. Most of the time I have to reglue all of
this back together.

So if you cut your blister pearl off and the nucleus pops out, no
harm done. Just glue it in, filling up the cavity completely with
glue. That adds strength, so the blister doesn’t break when hit in
normal wear. Use clear glue - the blister is translucent and will
take on the tint of your glue. You can make your own flat backing
piece if you want a professional look. Use a thin piece and round
the bottom edges so they won’t chip when glued or set.

Lauren