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Reference Needed Attention Gem Stone Experts


#1

Hello Everyone-

I have sort of a strange request.

I am looking for some sort of a chart or reference that will allow me
to derive the approximate gem weight of a given faceted or cab cut
stone from its measurements. I would prefer an online source for this
of course, offline would be fine too.

Thank you all in advance- Amy


#2

Amy, here is a web site with the formulas you need to calculate the
approximate weight of a faceted stone. You will have to know the
specific gravity for a particular gemstone material.

Using a spreadsheet, you can make your own table and let the
spreadsheet do the math for you. Have fun.

http://www.tradeshop.com/gems/estimate.html

Charles Heick


#3

Hi Amy:
(sorry my english)

There are 2 simple ways to obtain stone’s weight. 1�) you can buy a
scale, special to weight little stones (could be Tanita brand or
similar) in the provider’s jewlry stores. 2�) You can obtain the
volume of the stones measuring in a glass jag with marks to mesure
the level of water after and before to put the stone inside and with
this volume (the difference) you multiplicate by the density of the
stone (in any gemstone’s book) and obtain the weight. With any of this
method you can do your own chart of any type of stones.

Bye
Adriana Beniscelli
Eng.& Goldsmith


#4

Howdy Amy, This may not help much but Gemcad is a program which can
be used by faceters to design,alter and ‘play with’ faceted gem cut
diagrams. It will provide a formula (constant?) which can be used in
conjunction with the specific gravity (densitiy) obtained for the
material in question. It would require you to enter the design (or
find a very similar design from a database such as DataVue II), take a
measurement (usually the width) and know the SG of the gem material.
Then you could calculate the weight. If you will be dealing with
common shapes and sizes which are cut similarly to dimaonds you could
set up a ratio of the SG differences between diamond and the various
gem materials you’re working with and use the numbers from the diamond
charts as a starting point perhaps. I’ll bet this is already
available.(seems familiar to me,possibly from the back of a catalog or
something.) Download the above mentioned software from;
http://www.gemcad.net/ Carl 1 Lucky Texan


#5

Greetings to All,

There’s a great book called, ‘The Complete Handbook for Gemstone
Weight Estimation’ by Charles I. Carmona, GG., with a foreword by the
living gemology legend, Richard T. Liddicoat. It was published in
1998 and at 429 pages, it’s hard to imagine anything more
comprehensive. Both common and uncommon shapes like kites, rondells
and briolettes are included, along with diagrams, charts and
formulas. The book even includes guides to account for bulge factors
too.

It lists for $59.95 but it’s well worth the investment. I obtained my
copy through the GIA, I’m sure they still carry them through their
bookstore. An online catalog can be found listed under GEM
Instruments and Books at www.gia.edu.

Best Regards, Jeanette from Kansas where near 50 degree weather were
part of everyone’s Thanksgiving praises today…


#6

Hi Amy.

Sorry such a delay in this post but when our ISP made changes
recently our mail program quit its “send” function!

I have located a set of charts that I clipped some years ago from a
now-forgotten brochure. They use measurements (in whole millimeters)
to approximate the weight of round, oval and emerald cut faceted
stones of various gems. I have uploaded scanned copies to our Orchid
FTP site.

Although there is adequate resolution in the file to allow reading
it, I reduced the size of the image to make the file smaller for
transfer and don’t know yet how it will appear to a browser on the
Orchid site. If you are unable to enlarge the image there to a
readable size, you can right-click and save it to your machine and
view actual pixels (a readable size) or enlarge it a bit more. If you
don’t have photoshop or such, acrobat reader works fine.

HTH,
Pam Chott
songofthephoenix@pobox.com
www.songofthephoenix.com
www.silverhawk.com/ex99/chott