>All we know that quite a lot of “enhanced” shells (mostly cowries and
>conidae) are on the market or in private collections of cheated
>collectors: painted, coated, baked, repaired, polished shells, and so on;
>e.g., recently somebody talked about cypraea aurantium treated with acid
>and then polished; some years ago even Raybaudi was wrong in considering
>the specimens of the so-called cypraea lobettiana.
>My question is: how do you detect a fake shell? How can you discover if a
>shell was baked, or discoloured under the sun to make it an albino?

A true white variant is unlikely to be albino. It
is possible, of course, but it would be necessary
to examine the animal to tell. And unfortunately
the plethora of white specimens coming from the
Philippines, and no doubt soon elsewhere, are
fake... apparently produced by boiling the shells
in oil. Pterynotus miyokoae is a common one. I
did buy a white Telescopium telescopium collected
supposedly in Australia, and THINK it is a
genuine pale form, as the columella is
light-mauve-brown... but does anyone have a junk
specimen they can heat to tell me if the
columellar pigments are more heat-resistant than
the rest of the shell?

>How can you find out the result of Shell Doctors’ art? It would be very
>interesting to know more about methods of discovering frauds: any
>suggestion and/or opinion?
>
>     As a cowry and cone collector, I've come across quite a few 'doctored'
>shells and have learned some ways to figure out the authenticity of shell
>features.  I hope you will find these methods useful:
>
>- Painted shells - The painting techniques used to 'restore' dead or
>otherwise poorly patterned shells is getting increasingly sophisticated and
>professional.  One method I was quite impressed with is the layering of
>paint and clear or translucent resin to produce depth in patterns, much like
>you see in genuine cowry shells.  A magnifying loupe is useful in detecting
>unnatural looking brushstrokes or paint dabbling, but if you have a way of
>making a high resolution scan of the shell, you should be able to readily
>identify manipulated patterns, bubbles, or other problems.  I have used the
>scanner method to identify faked shells I have received in the mail and had
>them returned for refund.

Conus color-patterns are often complex and
usually quite sharp-edged... impossible to fake
convincingly (a x10 lens should show fakes up
easily). Spiral lines and fine collabral lines
(ie following growthlibnes exactly) will show
flaws in orientation if faked.

>- Tapping - light tapping of a highly glossy shell surface such as that of a
>cowry shell against your front teeth can expose a resin overcoat.  A genuine
>shell surface should give a crisp tap, while a resin-coated one might feel
>dull.

Yes, the varnish/paint will be softer than the
shell & your teeth. Or another shell from the
same dealer's shelves...

>- Look for continuity in ridges and growth lines - Cones and voultes are
>very often filed, and sometimes the workmanship is such that it is nearly
>impossible to tell whether filing has been done or not, especially if the
>lip is very sharp.  One way to check is to look for the growth lines along
>the lip.  The lines should be continuous from the anterior to the posterior
>of the lip.  They should not terminate abruptly part way.

The Marginellona gigas (=Sigaluta pratasensis)
marginellids offered by Molluscs Net/C&S auctions
are inevitably dead-collected (I won several),
and have been filed and POLISHED... the marks are
clear under magnification, as are bryozoan
etchings!

I HATE lip-filing... chips are infinitely preferable.

>- Layers - In species where a mantle covers over the shell and shell
>material is laid down over time, a layering effect occurs.  These layers are
>not apparent in a perfect shell, as the upper ones obscure the lower ones.
>However, if any cutting into the shell has occurred, you can see the
>layering.  As a recent example, I obtained what looked like an exceptional
>Cypraea mauritiana with a corrugated (scalloped) base. I have read accounts
>from very reputable shell dealers that they have seen live animals with such
>a base, so I decided to purchase the shell.  Later, upon inspection in
>bright sunshine, I saw the telltale layering I referred to above.  With
>further inspection, it was also clear that some of the corrugations were too
>finely and sharply cut to be natural.  The polishing done on the surface was
>perfect and it didn't even appear that any kind of coating was used.
>
>- Chemical test - Solvents, such as acetone, can be dabbed on a suspected
>spot to detect resins, which would dissolve or become cloudy.

Don't dab; dump the shell into acetone overnight.
There's nothing to lose, and the solvent won't
hurt the real shell or its pigments.

>- Baked shells - Sometimes it's more than obvious.  For more carefully done
>work, look under a magnifier for microcracks and nacre bubbles.

Easily done... I put white spots into a batch of
Provocator mirabilis by accidentally boiling them
dry. Note that they did not bubble or craze,
though this species has a thin overlay of
inductura over the entire surface. If you have
specimens, you can easily repeat this to check
for yourselves...

>- Sun-bleaching - For glossier shells, sometimes you'll get nacre bubbling
>and a dulling of the finish.  Also, carefully look within the aperture of a
>shell to see if there is darker, inconsistent color further inside.
>
>- Black light - I've never used this myself, but it makes sense that any
>resin or filler used on a shell should show up as a visual  inconsistency in
>the shell.

Ultraviolet. Very likely. The shell's pigments
may glow, but filler will be utterly...
vocabulary-strike strikes... unmatching.

>- Too perfect - Truly Gem shells are very rare if one follows the HSN
>grading standards in a strict manner.

The HSN standards are nonsense, except for the
Gem grade. I have yet to see a "gem" specimen
turn out to be true.

>It's hard enough to get cowries in
>true Gem quality, and I really do not believe in Gem Murexes.  Anyways, if a
>shell looks too perfect and has too exceptional a feature (size, appendage,
>coloration, pattern, etc.), it's time to be cautious.  Also, if certain
>parts of a shell look much too perfect to suit the overall quality of the
>shell, there's a good possibility of manipulation.

Watch for attachment-clusters, such as
Spondylus/Chama/Plicatula/barnacles on Hexaplex.
I recently received a H. cichoreus/Spondylus
which also had large barnacles attached... but
the barnacles looked wrong. Close inspection
showed that I could see the BASES of the
barnacles... a soak in water easily removed them
by dissolving the glue. And the (genuine enough)
bivalve/gastropod combo was much nicer as a
result!

The biggest fakes of all moneywise must be fake
sinistrals. One which came up on the list in
recent times was a certain listee's fake Cymatium
pileare, produced by cutting normal specimens up,
reorienting pieces, gluing and spraying on a
fuzzy fake periostracum. This could have been
caught immediately, as the species has a
periostracum with axial rows of strong hairs, but
the dealer and recipient probably did not know
this at the time (I did know, having collected a
very nice specimen a few years ago in Fiji, but
temporarily forgot). This dealer has other fake
sinistrals he sent me images of; he wasn't
certain about some of them.

I was recently contacted by a collector with
images of what appear to be a pair of fake
sinistral Turbinella pyrum. He says he has
x-rayed them and both appear to show columellas,
but he is taking my advice and will try to get
industrial-strength x-rays pf these two and some
normal chanks for control. I suspect that these
are fakes produced individually (not in a mold)
by rolling clay or plastic putty, thereby
creating a "genuine" columella.
I can pass on the images of these shells at
request, but will not name the owner without his
permission.

I doubt that any reputable dealer would knowingly
sell fakes as genuine... but it it surprising how
many decades some of them can be in business, and
still unable to spot a blatant fake. If you
receive one, return it for a refund... unless you
LIKE it as a curiosity. In which case the dealer
shoule still refund almost all of your money...
as I hope was the case with The Twisted Triton.

The ONLY alteration I can condone is repair of
breaks by gluing the broken bit back on IN
CORRETC ALIGNMENT and with a SUITABLE glue eg
cyanoacrylate (superglue). NO "rebuilding" of
missing bits or bits from other specimens.

Beware operculum replacement too... it is
inexcusable to fit the operculum from another
specimen, even of the same species. All too often
I buy specimens with too-small an operc of the
same species (or species
sufficiently-closely-related that I can't
tell)... and often from another species or even
family... or an operc fitted to a dead-collected
shell... or even an operculum fitted to an
inoperculate species eg cancellariid. And glued
in upsidedown, inside-out and usually to the
shell itself...
--
Andrew Grebneff
Dunedin
New Zealand
Fossil preparator
<[log in to unmask]>
Seashell, Macintosh, VW/Toyota van nut

----------------------------------------------------------------------
[log in to unmask] - a forum for informal discussions on molluscs
To leave this list, click on the following web link:
http://listserv.uga.edu/cgi-bin/wa?SUBED1=conch-l&A=1
Type your email address and name in the appropriate box and
click leave the list.
----------------------------------------------------------------------