Hello, Francesco, 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. - 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. - 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. - 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. - Baked shells - Sometimes it's more than obvious. For more carefully done work, look under a magnifier for microcracks and nacre bubbles. - 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. - Too perfect - Truly Gem shells are very rare if one follows the HSN grading standards in a strict manner. 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. This is just my two cents on the subject. I'm sure we can all learn plenty more from others. Best regards and aloha, Dave Lum >From: Francesco Guarracino <[log in to unmask]> >Reply-To: Conchologists List <[log in to unmask]> >To: [log in to unmask] >Subject: fake shells >Date: Sat, 25 Dec 2004 18:14:56 -0500 > >Dear friends, > >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? 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? > >All the best >Francesco Guarracino >Roma - Italy > >---------------------------------------------------------------------- >[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. >---------------------------------------------------------------------- ---------------------------------------------------------------------- [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. ----------------------------------------------------------------------