Top Diamond Simulant Myths....article in progress

#22
I certainly agree with the author that moissanite is not very similar looking to a diamond. The rounds with little body color are beautiful to my eyes and that is all I care about. The princess/square brillant are wierd cuts and I don't recommend them.
 
#23
Re: Top Diamond Simulant Myths....article in progr

2)Our CZ has carbon in it:

You can check with your local solid state chemist, who will tell you that fundamentally carbon and zirconium are not able to naturally bond on the molecular level due to their size difference. Hence, all claims like “our CZ contains 30% carbon” are impossible.

Asha uses the fact that carbon and zirconium are drastically different sizes to allow the amorphous diamond (carbon) to infuse/penetrate into the upper layers of the CZ core, so it does contain carbon via the coating process. However, that is very different than claiming carbon is naturally mixed in as part of the CZ formula itself, which is not doable.
I wouldn't write that: it is not so true.

It exists a solid solution between Zr(C, N, O).

Look at for some considerations:
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392001000200012

It means that the framework can accomodate, and it does, within some percentage and conditions, other elements witouth loosing the symmetry.

I would also change the paragraph where it is written that elements cannot stay in a framework because they are too different as sizes, it's quite funny.
The causes are related to thermodynamic and crystallographic considerations.

Regards
Wu_Ming
 
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#24
Re: Top Diamond Simulant Myths....article in progr

Wu Ming, could you please rephrase in non-scientific English? I'm afraid I don't understand your points here.
 
#25
Re: Top Diamond Simulant Myths....article in progr

Wu Ming: Ok, I had a look at your reference, and as far as I can tell, what Less said what true, in terms of CZ's used in jewelry. In the lab, carbon and zirconium may combine, but not in conditions stable and predictable enough to produce a usable crystal, and not without the addition of some other elements. So,the bottom line is that no CZ's on the market can contain carbon and zircon - the conditions of a jeweler's bench don't provide the "framework" you were referring to. If I've got this wrong let me know.
 
#27
Re: Top Diamond Simulant Myths....article in progr

Less,
when you say that it is not possible to produce a solid with zirconium and carbon ("it is not doable"), you do forget some tens of years of industrial processes related to the production of ZrC, widely used in the world.

I would like to highlight some points, because:

1. it is possible to produce a solid with Zr and C
(look the internet for ZrC)


2. C can bond to Zr easily, inside a ZrO2 framework (atomic lattice)

As reference, look at the Fig. 6 and the conclusion number 5
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392002000400011

The consideration that it is related only to crystals with powder dimension doesn't change the chemical considerations, it is only easier to work in lab with powder instead than with bulk crystals.

3. About SEM analyses(I hope EDX analyses) on materials cointaining C, I would take care.
Also the most advanced equipments have some problems in detecting quantitatively Carbon, because of its light atomic weight.
If the microprobe is not ad hoc prepared, and the technicians not experienced on carbon analyses, it is very easy not to detect properly the Carbon: it is the theoretical lower detection limit of the SEM-EDS analyses.

So:
If the Zr can easily bond to C, because it exists ZrC, and also are reported phases made of different mixing of Zr(C,N,O), it means that in a crystal, also of commercial interest, inside the framework(the atomic lattice) can exists areas of "pure" ZrO2 and of Zr(C,N,O). From the literature we understand that the overall symmetry it is not deeply changed, so the physical properties, the ones a jeweller can detect, will not be affected from such a chemical mixing.

I do not know who your local state solid chemist is, but, also over the internet, it is available some updated literature regarding the system Zr(C,N,O).


From a chemical point of view, it is credible to have a little percentage of C inside the CZ crystals.

I hope to have been of some help, in some very technical and not really important points, for your interesting divulgative work on CZ.


Regards
Wu Ming
 
#29
Re: Top Diamond Simulant Myths....article in progr

After seeing a lot of diamond simulant sellers making many of the same false claims, and customers falling for them, I have been working on an article called "Top 5 Diamond Simulant Myths" to help consumers seperate fact from fiction.

Its a work in progress, but I'm open for feedback on it before it gets posted more publicly.

Currently there are 5 common incorrect assertions I often see, but let me know about others that should be added.

Article (in progress) is here:
Top 5 Diamond Simulant Myths...

Best regards,
Less
Much appreciated for the detailed information Less, wish I came across this earlier before wasting over $800AUD for a ring by Gordon Max!


At the time of purchase, they specifically told me that their stones contain diamond particles, which now I realise is very misleading to say the least! Anyway, it was an expensive lesson learnt. I have forwarded your article to family and friends so they can be better educated on whats available out there on the market.
Thank you once again!
 
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