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 Post subject: can diamond tester be fooled by some chemical
PostPosted: Thu Dec 15, 2016 9:56 am 
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Hi all

I have heard that CZ or moissanite can be picked up as diamond by diamond tester, when they are coated with some material probably some special chemical. If that is the case then how to identify fake from real ones without sending the stones to lab?


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 Post subject: Re: can diamond tester be fooled by some chemical
PostPosted: Thu Dec 15, 2016 4:41 pm 
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If you can measure the specific gravity of the stones, you are saved. They all are different.


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 Post subject: Re: can diamond tester be fooled by some chemical
PostPosted: Thu Dec 15, 2016 5:31 pm 
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Moissanite can, without any coatings, read as diamond on a thermal tester. Its double refraction and SG will separate.

Manufacturers of "diamond coated" CZ make claims that this material reads as diamond with a thermal tester. :^o That has been disproved.


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 Post subject: Re: can diamond tester be fooled by some chemical
PostPosted: Fri Dec 16, 2016 5:22 am 
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Diamond tester can also read natural topaz, tested on light yellow rough chunk of topaz. Happened just on single piece.


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 Post subject: Re: can diamond tester be fooled by some chemical
PostPosted: Fri Dec 16, 2016 1:55 pm 
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Indicates an unreliable thermal tester, Gabroo. :wink:


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 Post subject: Re: can diamond tester be fooled by some chemical
PostPosted: Fri Dec 16, 2016 4:16 pm 
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Where did you get a light yellow chunk of topaz?

I've heard of testers being fooled by cold topaz, but it may be more myth than legend.

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 Post subject: Re: can diamond tester be fooled by some chemical
PostPosted: Fri Dec 16, 2016 4:28 pm 
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MJ_curious wrote:
Hi all

I have heard that CZ or moissanite can be picked up as diamond by diamond tester, when they are coated with some material probably some special chemical. If that is the case then how to identify fake from real ones without sending the stones to lab?

Just look at the stone and estimate the B:D ratio.


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 Post subject: Re: can diamond tester be fooled by some chemical
PostPosted: Sat Dec 17, 2016 2:53 am 
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Believe me Barbra, you cannot trust any gem equipment which will fool you exactly when your in need, specially presidium ii...tested and failed.
Such broken rough pieces of different kind of stones are found scattered in Gilgit & Kashmir mountain ranges. Shepherd's usually pick up these 5 to 10 ct chunks laying on the ground. Mostly used as for necklace beads..


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 Post subject: Re: can diamond tester be fooled by some chemical
PostPosted: Sat Dec 17, 2016 3:14 am 
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That is neat. All the ones from those areas I have tested have faded to colorless pretty quickly.

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 Post subject: Re: can diamond tester be fooled by some chemical
PostPosted: Sat Dec 17, 2016 11:16 am 
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Don't know from whom you bought those topaz or other crystals, anyway, i'm from Punjab Pakistan and i do not deal any mineral dealer/seller who is selling on line ...Because i do not know them, i have my own reputable sources. You should find good dealers in Pakistan,


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 Post subject: Re: can diamond tester be fooled by some chemical
PostPosted: Mon Dec 19, 2016 7:31 am 
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My diamond tester can distinguish between diamond, moissanite and CZ. The stone i checked was of 3 carat, room temperature and indicated as diamond on tester. but SG was different.

Many a times we dont have SG measuring equipments, how to avoid scenarios like this and what the heck was that stone?


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 Post subject: Re: can diamond tester be fooled by some chemical
PostPosted: Mon Dec 19, 2016 10:38 pm 
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Specific Gravity shouldn't be too hard to measure!
All you need is a scale, some wire to bend into a jig, and a cup or beaker of water...
Weight the stone on the scale. This is the dry weight of the stone.
With my platform scale, I have a wide circle of copper wire on the scale.
From there, I come up, and bend the wire over and down a little.
I either bend or solder a small basket on the end of the wire.
A cup of water is then brought up into the basket (I usually mark a spot on the wire and then "tare' it there, unless I'm using a chemistry ring stand or other repeatable jig to immerse the stone.
Once I "tare" this, I then drop the stone into the basket to get a wet weight.
Subtract the wet weight from the dry weight, then divide the dry weight by this difference in value.
This is your specific gravity. Not really much to it. It's good to have a very accurate scale for this!


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 Post subject: Re: can diamond tester be fooled by some chemical
PostPosted: Wed Dec 21, 2016 4:15 pm 
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Tom Herman wrote:
Specific Gravity shouldn't be too hard to measure!
Not really much to it. It's good to have a very accurate scale for this!

One does not need an accurate scale of any kind to measure SG. One can simply use a stick, a piece of thread, a couple of washers and istructions for making a Hanneman Relative Density Balance, which I will send to anyone who sends their name, address, and a self addressed stamped envelope to me at
264 Soledad Dr.
Monterey, CA 93940.

Merry Christmas


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 Post subject: Re: can diamond tester be fooled by some chemical
PostPosted: Fri Dec 23, 2016 8:59 pm 
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I was always taught not to trust any one reading. Take two or three, S.G., hardness, R.I. if you have a calibrated microscope and see where they all point.


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 Post subject: Re: can diamond tester be fooled by some chemical
PostPosted: Fri Aug 18, 2017 7:39 pm 
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Thats funny I just posted about this in the "diamonds" section. There's a new type of lab-grown stone called "Amora Gem" which can fool both Diamond AND Moissanite testers! I've actually tested them myself.


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