[Be cautious] C-3 Moissanite Tester

Be cautious - C3 is marketing their tester as being 100%
accurate, but I have had it fail on three separate occasions.
Repeated tests were done correctly on the same stones, but each
time the tester indicated diamond. Use a polariscope or
gemscope to verify stones instead of trusting the tester.

Another argument for the Diamond IDer. I know you purists don’t
like the idea of a “destructive” test, but the point of the
probe is so sharp, and the mark on the stone is so small the
test mark is very hard to locate without magnification.
Especially if the suspect stone is tested on an inconspicuous
location such as the girdle. Plus, the IDer is completely
portable and pretty much foolproof since it doesn’t rely on
batteries or any other energy source. The size and shape of a
dental probe makes the IDer easy to stick in the pocket and off
you go.

Drop it - no problem. No sensitive electronics to worry with.
Dirty stone - no problem. Not holding your tongue right while
using the tester - no problem. I don’t have any of these for
sale anymore, so this isn’t an advertisement - I just couldn’t
resist the friendly jab at some of the "wonderful technology"
that has become so hard to live without. Sometimes there is
much to be said about getting back to the basics.

To all, With all due respect to Aufin (?), I really believe there
is no acceptable excuse for any form of destructable testing for
a diamond substitute. You are causing damage to another person’s
property, regardless of the size of that damage, and are liable
for same. If you are performing work on a customer’s piece of
jewelry, and need to determine the nature of the stones, then you
are obligated to educate yourself as to the proper method of
stone detection. There are occasions when we cause damage
unintentionally, but never any excuse to do so “on purpose”.

Hopefully my Doctor does not subscribe to this theory! JMF

Regarding Moissanite testing, I have not seen any, but given the
published values for its birefringence, the facet doubling ought
to be clearly seen, if not thru the table, then try two other
axes at (close to) right angles to the table. If it’s
moissanite, I can’t see how you would fail to see the doubling.
Look thru a crown main or break or similar just above the girdle
at the pavilion mains or breaks opposite just below the girdle.
There may also be characteristic inclusions (anyone??), and my
guess is that there is not the typical “sugary” appearance to
the frosted girdle usually seen on diamonds. Q.E.D., without
the $500 tester. You should acquire the experience to do this
visual ID if you’re in a position to encounter the stuff. If
you don’t have the experience, you need the tester. Getting the
experience shouldn’t cost you much more than an hour’s work and
access to a moissanite sample or two and a diamond or two.
Pretty good hourly rate on your time, no??


Hi all, I had the opportunity to look at a piece of cut
Moissanite at the S.A Jewellery fair. The facets showed the
typical slight rounding that one gets with a soft stone (in
comparison to diamond) On the exact edge where the two facets
meet there is a small radius, which is not there with a diamond
(it being much sharper, to me ).I speak from only one stone
been seen, but to me that has always been the way of seeing if
set , small stones are diamonds or not. Cheers Hans.

SEROL-WANA Designer African Jewellery
P.O.Box 266 Kasane Botswana
Tel: +267 651011,650555 Fax:+276 651168
     The facets showed the typical slight rounding that one
gets with a soft stone (in comparison to diamond) 

This is usually the first indication that I look for. It,
however is unreliable at best and in the case of synthetic
moissanite, is usually no indicator at all. Most of the stones
that I have seen have razor sharp facet junctions. I presently
have about 20 stones in my posession and offered a demonstration
to a friend last night and this was a test that I didn’t even mention.

I’ve seen a few. To start with, I’ll say the things are harder
to spot than C.Z. The C axis of the material is generally
perpendicular to the table, so you don’t see facet doubling
straight on. but it’s clearly visible at a 45 degree angle to
the table, looking into the crown at back facets. And while it
doesn’t display that dramatic "obviously something wrong"
dispersion and dark look of C.Z., a trained eye will still find
that it’s not quite right. Reflections, dark areas, etc, aren’t
quite where you expect, though you might have a hard time putting
your finger on just what or where. The hardness is good enough
so that the obvious rounding on facet edges and the girdle is not
there, but under a microscope, you can still find enough rounding
of facet edges to at the least, make you suspicious. The facet
doubling is the big clue. Table down, the appearance also is
wrong, but this is something you have to learn to see.

Note that the facet doubling can be difficult to see with a
loupe, in smaller stones, and also in some non-round stones. I
almost missed it in a carat sized princess cut, even when looking
for it. Had I not already known it was a moissanite, I might not
have looked hard enough to see it, with just a loupe. Under a
microscope it was obvious, but just sitting at the bench, not so
much. And a small (fifteen point) side stone was small enough
that even careful looking with a loupe left me unable to see for
sure whether it was a diamond or not, even knowing it was not.
Again, under the scope, it was obvious.

With loose stones, a bottle of methylene iodide is useful.
Diamonds sink in MI. Moissanites float. (C.Z. also sinks, much
faster than a diamond) Be reasonably careful with MI, however.
It’s a somewhat toxic liquid. GIA/Gem Instruments sells small
bottles of Methylene Iodide intended for such specific gravity
testing if you need a source.

Peter Rowe

I have heard if you bring a heat source (candle flame) close to
a moissanite stone it will turn a bright yellow and then revert
to the original colour when it cools. Has anyone heard of that
test or tried it? Regards,