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Synthetic zircon tests positive with diamond tester


#1

Does anyone have any on synthetic zircon and faceting
one? The piece I have seen is apparently old and pink. It also tests
as a diamond with a diamond tester.

Anne


#2

A synthetic zircon has the same chemical, physical and optical
properties as a natural zircon. So whatever the faceting angles for
zircon are should work. however, you make me ask, how do you know it
is a synthetic zircon? You say that a diamond tester shows positive
diamond. A simple polariscope test for single vs double refraction
can at least determine if the stone may be diamond (single
refraction) as opposed to zircon (double refraction).

John


#3
Does anyone have any on synthetic zircon and faceting
one? The piece I have seen is apparently old and pink. It also
tests as a diamond with a diamond tester. 

Yes, it is an old trick. It is also shows that reliance on quick and
easy methods are fraught with danger. You have stone which has a
layer of diamond film deposited on it’s surface. It will fool diamond
tester every time.

Leonid Surpin
www.studioarete.com


#4

i think you should try a different diamond tester on the stone you
have and you should try the diamond tester you have on more zircon.
call around and see if anyone you know has a refractive index tester.

goo


#5

You dont say what sort of diamond tester so I presume that it is one
of these that measures thermal conductivity. Diamond if a brilliant
conductor of heat and zircon is a very poor one- cubic zirconia being
even worse. Zircon is zirconium silicate which is different from
cubic zirconia, it has a different crystal structure and optical
properties so I am wondering if you have the two confused but
neither will test positive on a diamond tester. Commonly a false
positive is given when the probe touches soemthing else when testing.
With a set stone the obvious candidate is the setting itself so it
would lead me to ask about how big is this piece of rough and how was
it held when tested. Cutting diagrams are available for both zircon
and zirconia- the latter is very popular for fancy cuts because of
its high dispersion.

Nick royall


#6

A synthetic zircon would have the same chemical, physical and
optical properties as a natural zircon, if there were any synthetic
zircon, which I doubt there is. A natural zircon will not test
positive with a diamond tester, so a synthetic would not either.

Richard Hart G.G.
Denver, Co.


#7

Do you possibly have a synthetic cubic zirconia (SR, singly
refractive)? To my knowledge they do not synthesize zircon (DR,
doubly refractive).

If a syn cz or zircon are testing as diamond on a dia tester, the
tester’s sensitivity is set too high, the probe is damaged or
possibly a weak battery. Try the tester out on a known diamond and
compare to a synthetic corundum (sapphire). The diamond tester works
on the pricipal of heat conduction and diamond conducts heat better
than most other gems with synthetic moissanite (silicon carbide DR)
being close and sapphire/ruby (DR) being a distant second.

Arthur Anton Skuratowicz
JewelryTrainingCenter.com


#8

Hello,

Moissanite also give the same reaction as diamond to diamond tester.
http://www.ganoksin.com/gnkurl/kd
Maybe your stone is a moissanite.

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


#9
The diamond tester works on the principle of heat conduction and
diamond conducts heat better than most other gems with synthetic
moissanite (silicon carbide DR) being close and sapphire/ruby (DR)
being a distant second. 

Moissanite will test positive with a diamond tester, same as diamond,
so it is not close, it is the same. Only two gems conduct heat,
diamond and Moissanite. Light bulbs are either on or off, there is no
almost on or almost off, off is not almost on. Sapphire and ruby will
never test positive, so it is not a distant second. If it would be a
distant second, so would garnet, glass, plastic and cheese.

Richard Hart G.G.
Denver, Co.


#10

Hi,

i think you should try a different diamond tester on the stone you
have and you should try the diamond tester you have on more
zircon. call around and see if anyone you know has a refractive
index tester. 

You didn’t say what type of stone tester you were using.

There are 2 different types of testers usually used to test gem
stones.

One typically called a diamond tester, uses a probe that’s heated
electrically & when touched to the diamond, the diamond absorbs the
heat verifying it’s a diamond. Diamond is the only natural stone to
have this property. Moissenite will also test as a diamond, but it is
doubly refractive & that property can be detected using a loupe.
Diamond is singallly refractive.

The other type of stone tester is a reflective tester. It applys a
light to the polished surface of the stone & uses the reflection to
determine the stones id. These testers output can vary depending on
the quality of the stones polish.

Dave


#11
Only two gems conduct heat, diamond and Moissanite. 

Richard, you’re painting a picture that’s a bit to black and white,
with no grey.

Diamond and Moissanite are indeed the only stones that test positive
on the typical thermal diamond tester, but even they are not
identical to each other (diamonds has higher thermal conductivity
than moissanite). You statment implies that all other gems conduct no
heat, and that’s just not true. virtually all materials other than
hard vaccuum (which is a non-material) conduct heat to some degree or
other. Some conduct very little, and are good insulators. Others
conduct more. Each material has it’s own level of thermal
conductivity, just as metals have differing thermal conductivity
(silver, for example, is a much better thermal conductor than karat
gold or platinum).

It is true, though, that diamond and moissanite pass the diamond
testers, while other gems should not. But that’s only one measure,
and if you happen to use a sensative enough thermal tester, you can
also distinguish between diamond and moissanite this way.

Yeah, I’m nitpicking again, but some might have drawn a false
impression from your otherwise accurate wording.

Peter


#12
Moissanite will test positive with a diamond tester, same as
diamond, so it is not close, it is the same. Only two gems conduct
heat, diamond and Moissanite. 

All gems conduct heat, all matter conducts heat. The thing that a
diamond tester of this type is measuring is how well it conducts
heat. Thermal conductivity, k, is the property of a material’s
ability to conduct heat. Diamond has an amazing ability to conduct
heat, its k value is over 900, silver the most thermally conductive
metal only has a k value of 429. Diamond and moissanite with a k
value of 830 both have high thermal conductivity in relationship to
other materials that might be used as diamond stimulants. Older
thermal conductivity tester designs were not sensitive enough to
distinguish between the two. The newer designs have corrected for
this and can distinguish diamond from moissanite.

James Binnion
James Binnion Metal Arts


#13

Peter,

It is true, though, that diamond and moissanite pass the diamond
testers, while other gems should not. But that's only one measure, 

One measure of what?

Your statement implies that all other gems conduct no heat, and
that's just not true. 

I do not believe what I wrote implied any such thing. In the context
of using a thermal tester, only moissanite and diamond respond
positive. What is implied is that all other gems do not test positive
with a thermal tester. That is true.

The original post was about a “synthetic zircon” being tested with a
diamond tester and getting a positive for diamond. Someone replied
with:

The diamond tester works on the principle of heat conduction and
diamond conducts heat better than most other gems with synthetic
moissanite (silicon carbide DR) being close and sapphire/ruby (DR)
being a distant second. 

I believe in the context of a discussion about someone getting a
positive indication on a “synthetic zircon” using a diamond tester,
I feel I was clear that diamond and moissanite are the only gems that
test positive as diamond with a thermal tester… That is true. No
gray there. That all gems can conduct some heat is meaningless in the
context of using a diamond tester. Other than separating diamond and
moissanite from all other gems, a diamond tester is useless for
identifying any other gem. No gray there.

I felt I was clear that if only diamond or moissanite test positive,
ruby and sapphire cannot be a distant second. They are not on the
list of gems that can be identified by thermal conductivity. No gray
there.

The discussion was not about how to identify diamond from moissanite
or either from ruby, or sapphire.

Prior to moissanite, only diamond would test positive with a thermal
tester, the only reason for the thermal tester, in my opinion, was
when C.Z.'s came along. Gemological testing advances in relationship
to the synthetics and stimulants that are developed that can be
mistaken for diamond. Diamond is the only natural gemstone that I
know of that will test positive with a thermal tester.

Richard Hart G.G.
Denver, Co.


#14
I felt I was clear that if only diamond or moissanite test
positive, ruby and sapphire cannot be a distant second. They are
not on the list of gems that can be identified by thermal
conductivity. No gray there. 

My Presidium DiamondMate-A indicates corundum as a semi-positive,
that is the scale of red lights are lit up half way along the scale
and the green does not light up.

Diamond goes straight to the green lights along with a ‘beep’. I
have not tested it on Moisonnite, and no other stone that I have
tested gives any resopnse.

Ruby and sapphire are a measurable shade of grey according to my
little thermal tester and I find it a useful feature. I think the
general heat tolerance of a stone is directly proportional to it’s
thermal conductivity. Diamonds are very heat tolerant, ruby/sapphire
need more care and are more risk when heating. I have soldered 9ct
claws directly onto a CZ using 9ct easy solder provided the heat is
not too intense, and the heating and cooling is slow and gentle.

Regards, Alastair


#15
Ruby and sapphire are a measurable shade of grey according to my
little thermal tester and I find it a useful feature. 

So I assume synthetic and natural corundum will give the same
"semi-positive" indication with the Presidium Diamond Mate?

Google Presidium DiamondMate-A and it does say you can use it to
separate sapphire from iolite, tanzanite, ect. It does not mention
testing ruby for some reason.

If synthetic and natural corundum both give “a measurable shade of
gray”, what knowledge do you derive for a positive identification,
and how do you separate natural and lab created sapphire?

There is a simple observable positive identifiable visual
characteristic to separate sapphire from any other gems stone, and it
can be used to separate natural from synthetic.

There is no shade of gray.

In Gemology there is scientific method or ignorance. Half-assed
methods result in half-assed results. My opinion is abased on 6
months at G.I.A., five days a week, eight hours a day, and 34 years
of experience.

Lenoid mentioned diamond coated gem could test positive with a
diamond tester. I talked to someone who is an gem appraiser and he
said that a diamond coated gem will not have enough mass for a
thermal tester to test positive.

I can separate a diamond from moissanite or CZ with just my eyeball.
I usually only use a thermal tester in front of a customer for take
in for repair so there is no ambiguity later about what was in the
jewelry when it was brought in for redesign or repair.

Richard Hart G.G.
Denver, Co.


#16

The Presidium DiamondMate-A gives the same reading for ruby and
sapphire, both natural and synthetic.

Alastair


#17

some of these electronic testers develop a type of buildup on the
metal tip causing a false reading. This can be corrected you must
clean the metal probe tip by lightly touching and rubbing the end of
the tip on clean paper to remove the corrosion or whatever is formed
on the metal tip of the tester. There are times which i have used my
tester without doing this and the testor will give a green light or
positive diamond response when i touch it to my finger tip - goo