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How To Tell How Good A Diamond Is


TinnaGary
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How to tell a diamond's treatment? Generally speaking, if we say a diamond is good, we are always saying the material and the treatment are good. But the fact is , sometimes, we can hardly tell how good the diamond is treated. So, do you guys know any tool can do this job?

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What do you mean by "treatment"?

 

The majority of diamonds for sale are "treated" in the sense that they are cut, but as gemstones go there are relatively few diamonds that are enhanced through thermal treatment or filling. In general a reliable lab report that does not indicate treatment (in this second sense) is the best "tool" a consumer can use; detecting some treatments takes a fair amount of expertise and very expensive equipment.

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Identifying filling is relatively easy and a competent gemologist can usually do it in under a minute with very few tools.  That said, it does take a bit of practice and if you're making an expensive purchase decision based on the answer, I strongly recommend relying on a pro.   HPHT, which is a color treatment, requires advanced instrumentation that cost tens or hundreds of thousands of dollars.  Very few if any jewelers have it.  For that you want to rely on a qualified and equipped lab.  New treatments come out routinely.  There's one in the wings right now for example.  The labs are being tight lipped about it and it's unknown what it even is.  No doubt it'll get worked out but it may take a while.  For consumers the answer is straightforward enough.  Rely on the lab, not the seller, and use a lab that YOU find to be credible.  There are fakes.  The safest bet is GIA, which is also the most common.  It's not there aren't other qualified and skilled people out there but if the seller is asking you to rely on someone else, the question in the back of your mind should be 'why them?'.

 

It's possibly worth noting that identifying if a diamond is 'good' or not is not the same as spotting certain treatments.  Diamonds vary wildly from one to the next and treatments are only one of the issues. 

Edited by denverappraiser
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As I read your question again I think of another possibility. Are you asking how to decide within the universe of treated diamonds, which one is the 'best'? That's a giant can of worms. There is no accepted scale and methodology varies wildly between graders. The key is to rely on a grader that YOU trust. Buyer beware. I've seen stones that some seller called VS that I've called I-2.

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To dispel a myth that seems to be created here: some fillings and treatments (in jade and diamond) can be detected using UV lights, some cannot.

 

Even for those that can be detected using UV, bear in mind that not all UV light sources are equal, and some materials that fluoresce to LW UV are inert to SW and vice-versa; some natural gems and minerals are (as species or specimen) fluorescent on their own and the characteristics of fluorescence in treated materials are often not easy to determine - it takes knowledge and training that not everybody has. And occasionally equipment too: see discussion above about HPHT detection: it still relies on spectrographic information...

 

Incidentally, two mentions of the same vendor (of UV lights) by new posters within a day of each other and for no good reason (UV lights are available from hundred of vendors, including some that are significantly more relevant to a diamonds forum) looks suspiciously like shilling, so I have reported the posts for moderation. Apologies if this offends, but there have been a fair few people not willing to play by the rules...

Edited by davidelevi
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To dispel a myth that seems to be created here: some fillings and treatments (in jade and diamond) can be detected using UV lights, some cannot.

 

Even for those that can be detected using UV, bear in mind that not all UV light sources are equal, and some materials that fluoresce to LW UV are inert to SW and vice-versa; some natural gems and minerals are (as species or specimen) fluorescent on their own and the characteristics of fluorescence in treated materials are often not easy to determine - it takes knowledge and training that not everybody has. And occasionally equipment too: see discussion above about HPHT detection: it still relies on spectrographic information...

You hit the point!

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  • 1 month later...

To dispel a myth that seems to be created here: some fillings and treatments (in jade and diamond) can be detected using UV lights, some cannot.

 

Even for those that can be detected using UV, bear in mind that not all UV light sources are equal, and some materials that fluoresce to LW UV are inert to SW and vice-versa; some natural gems and minerals are (as species or specimen) fluorescent on their own and the characteristics of fluorescence in treated materials are often not easy to determine - it takes knowledge and training that not everybody has. And occasionally equipment too: see discussion above about HPHT detection: it still relies on spectrographic information...

 

Incidentally, two mentions of the same vendor (of UV lights) by new posters within a day of each other and for no good reason (UV lights are available from hundred of vendors, including some that are significantly more relevant to a diamonds forum) looks suspiciously like shilling, so I have reported the posts for moderation. Apologies if this offends, but there have been a fair few people not willing to play by the rules...

Great point. Thanks for the elaborate explanation @davidlevi!

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Here is a link to some tools that the top labs use in screening for treated diamonds.  

 

https://www.iidgr.com/en/Services/verification-instruments/

 

 

Fluorescence is used in the screening process but it is is a little more sophisticated technology than a UV flashlight  :)

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In the start, it was funny but got good knowledge from @davidelevi. That person seems to be crazy. :P

I read a few articles which tell how to test if a diamond is real - method other than GIA Certification.

Read here:

http://www.wikihow.com/Tell-if-a-Diamond-is-Real

http://www.businessinsider.in/5-Ways-To-Spot-A-Fake-Diamond/articleshow/45914014.cms

https://www.cutratediamonds.com/best-way-test-diamond-real-without-damaging/

 

I liked the fog test. :D

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What we do earlier was that if a diamond is scratched against mirror it mirror gets scratched, it was the sign of real diamond. However with time this method was also failed as some duplicate diamonds able to scratch against mirror. Now the best test is electronic test called as Diamond testers. It can conduct the thermal conductivity of the diamond. 

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What do you mean by "quality"? And which tools are you referring to?

 

A piece of glass to be scratchedd is "a tool", but it's useless; the spectrum analysers that Bryan has linked above (in the meantime changed to https://www.iidgr.com/instruments/home/) are quite good, but expensive. A loupe is not expensive and can help a lot, but it needs training.

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The best tools are knowledge, experience, and using the gemological laboratories appropriately.  It is unwise to rely solely on simple devices or tests.  If you are going to trade in diamonds to any extent at all, solid training is a must, and verification at the lab is almost always part of the process for any significant diamond.

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The tools that you are discussing, I want to know how effective and genuine can these tools be to determine a diamond's quality.

Certain qualities are pretty easy. Is it real, as opposed to fictitious, can be done by simply looking, although that’s not always easy to arrange. I mention that because most people don't see that as a 'test' when, in reality, it's one of the most important. A diamond is not the same as a photograph of a diamond. Dimensions can usually be directly measured with a micrometer, but that takes a micrometer. That’s equipment. Similarly, weight is easy enough with an unmounted stone but it takes a scale to do it accurately. More equipment. With mounted stones it’s a matter of estimating, which can sometimes introduce terribly important limitations, not the least of which is the above mentioned micrometer.

 

The minimum level of equipment for a gemologist is pretty low. A loupe, a pair of tweezers, a decent light that you’re familiar with, a cleaning cloth, a micrometer, a calculator, and a scale. With a bit of practice you can go a long way with that, but it won’t answer everything that falls under the umbrella of 'quality' and one of the most important issues is to understand your own limitations based on the tools and skills being applied. At the other end is a full lab. You can literally spend millions on training and equipment, and some labs do exactly that. With certain quality calls, it's required.

 

In the end, it's not usually the tools that are the issue. It's the user.

Edited by denverappraiser
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  • 1 month later...

I know a few stores that are selling quality diamonds with certicatation like - [removed names; suspect spamming]

 

"a few"? There are literally thousands of online dealers, and those two would not be on the top of my list of recommendations...

 

Are you affiliated with either of them - specifically the Houston one?

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One technique involves placing the gem on  a newspaper or other printed text  real diamonds refraction of light is  so much that you wouldn't be able to see any lines, circles or full letters coming through. But a diamond that's cut too shallow may produce inconclusive results.


Secondly, Another test requires breathing on the gem like we do in a mirror. Diamonds are good  conducting heat, so the fog your breath creates should clear up almost instantly. However, a synthetic rock called moissanite can pass this test.


If you still have doubt on these tests then the other option available is through "diamond testors"


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