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Opinions on diamond testers

I’ve been on the retail side for several years, (only recently
gotten serious w/ GIA gemology/grading classes, etc) so I’m somewhat
intelligent, but not confident in my identification skills. I’m now
getting so many requests off the street, to buy diamonds, I can no
longer ignore them, and so was thinking of buying a Tester. The $200
seems like a small investment considering the cost of a mistake. I’d
like to know the pros/cons and opinions of your experiences with
them/their accuracy and if possible any thoughts on CERES Dual XL
versus GemOro UltraTester II. I do appreciate your help!

My advice has nothing to d with your question but everything to d
with your business one you obtain a tester. Having tested the stones
for a prospective seller, do not let them be taken away and brought
back without re-testing the stones. It has been known to happen that
the stones have been replaced with paste or another look-alike with
the result that you supposedly purchase diamonds but receive white
topaz. Nice stone but not a diamond.

Make sure it can test for Moissonite. A tester is best used to
confirm your opinion of what it is based on examination and as a
demonstration to the doubtful customer, as opposed to a final
authority. They are not always 100% accurate, not even the best
ones. I would add that a diamond tester is not a place to try to save
some money. You get what you pay for.

I can’t speak to those specific testers, although the Ceres
Czechpoint was a good tester. Didn’t test for Moissonite, which is
probably why they have a new model. I have a new model Presidium
MultiTester. Seems to work pretty well.

Just to reiterate, use a diamond tester only to verify what you
already think. Look at things like facet junctions (they’ll look
slightly rounded on simulants, crisp and sharp on diamond), the
girdle for any chips or nicks, and especially naturals and for

Dave Phelps

I’m not familiar with how to post on orchid, so I’m giving it my
best shot…

My name is Cynthia Pennell, my dad was Neill Pennell a.k.a Neil the
Jeweler…some of you may have heard of him, and probably also heard
that he passed away a few months ago. I’m coming to the point with
my dad’s estate where I need to sell the jewelry he had in his store.
I don’t really know how to go about this, and would appriciate any
advice from anyone. I know my dad occasionally attened jewelry shows
in NYC and wasn’t sure if that would be a good thing to attend, or
really what I should do. Where I live there isn’t too much of a
market for jewelry, and there are about a good 5 or 6 jewelers in
the area people can go to who can do repairs if any items break. I
would do ebay but I’m always skeptical with expensive items on ebay,
I’ve gotten taken advantage of a few times.

Anyway, if anyone has any ideas or advice for me as to how I could
find ways to sell the items I would really appreciate it.

Also, if anyone knows anyone (or yourself) who is looking for
showcases for a store front. My father had I think either 7 or 8 show
cases in his store and now I have them sitting in a storage unit.

I have no experience in the jewelry business so I really could use
any advice. Unforunately, as talented as my dad was…he didn’t pass
his talent on to any of his kids.

Cynthia Pennell


Make sure it can test for Moissonite. 

A diamond tester doesn’t have to test for Moissonite. Moissonite
will test as a diamond.

After testing with the diamond tester & getting a positive reading
check the stone with a loupe. Moissonite is doubly refractive;
diamond is singly refractive.

In a doubly refractive stone the intersection of the pavilion facets
will look like there are 2 intersections.


A diamond tester doesn't have to test for Moissonite. Moissonite
will test as a diamond. 

That is absolutely true for older style thermal testers, which is
exactly why you should get a new model tester that CAN separate
moissonite. Moissonite is the one simulant most likely to fool you,
especially if your tester is unable to distinguish it from a diamond.
In smaller stones especially it can be difficult to make out the
double refraction. This is the only reason we got the Presidium Multi
Tester, it does distinguish between moissonite and diamond where our
trusty old Ceres CzechPoint did not. Again, it is most important to
understand that a diamond tester, any tester, should be used only to
back up your opinion derived from examination.

Dave Phelps

Hello, The diamond testers test if the stone is diamond or not. You
have to have also another tester for diamond or moissanite. I have
some in my website, maybe it will be usefull to you:

Kind regards,
F. Oya Borahan GG. FGA. DGA.