1. Dec 27, 2004

### Will

Is it true that gem quality man made diamonds are possible? How can they tell the difference between an industrial grade and gem quality and how do they grade them? I think the clearer the better and that the defects have to do with elements/compounds other than carbon. Any more info would be cool.
Does diamond have the highest index of light refraction? Thats what gives it its bling-bling right, the fact that the light just keeps bouncing around in there? And what is cubic zirconium, like is it also made of carbon but a different crystal structure, and how does its light refracting ability and clarity compare to the real thing?

2. Dec 27, 2004

### Astronuc

Staff Emeritus
Here is some information on man-made (artificial) diamonds, rutile, and zirconia.

Rutile is one of the few crystals that has a higher index of refraction (n = 2.605 - 2.901) than diamond (n = 2.418) - http://mineral.galleries.com/minerals/property/ [Broken]

Rutile is TiO2 crystalline - http://mineral.galleries.com/minerals/oxides/rutile/rutile.htm [Broken]
for crystal structure of TiO2 - http://www.webelements.com/webelements/compounds/text/Ti/O2Ti1-13463677.html

Zirconia (ZrO2) is similar - http://www.azom.com/details.asp?ArticleID=133 [Broken] - "In order to manufacture zirconia components, it is necessary to 'lock' the material wholly or partially into the cubic form by the use of additives or stabilising agents".
But, index of refraction of Cubic Zirconia = 2.21, slighly less than diamond, but relatively close.

Also see - Diamonds vs. cubic zirconia

This site (http://www.glenbrook.k12.il.us/gbssci/phys/Class/refrn/u14l1d.html#index [Broken]) mentions GaP as having the highest optical density or n=3.5

For discussion of diamonds and their design, see - http://www.folds.net/diamond_design/

Here is an article on 'artifical' gem quality diamonds - http://www.wired.com/wired/archive/11.09/diamond.html - which is a relatively recent development.

Most artificial or industrial diamonds have many other uses than gems.

See - http://minerals.usgs.gov/minerals/pubs/commodity/diamond/

Last edited by a moderator: May 1, 2017
3. Dec 28, 2004

### Staff: Mentor

I think he meant real diamonds - as in carbon. Zirconia aren't, "industrial diamonds" are. AFAIK, "industrial diamonds" cannot be made to "gem quality."

4. Dec 28, 2004

### Astronuc

Staff Emeritus
In the article on 'artifical' gem-quality diamonds - http://www.wired.com/wired/archive/11.09/diamond.html - the synthetic diamonds of gem-quality are made of carbon.

In the article there are two comments:

then later on

Gemesis has made gem-quality artificial diamonds from carbon. However, the example cited is yellow diamonds. I don't know if they can make white diamonds.

5. Dec 28, 2004

### omagdon7

They can make clear diamonds but colored diamonds sell for more. The technology was developed at the University of Florida by a professor in the MSE department who's name I don't recall.

6. Dec 29, 2004

### Staff: Mentor

I'm not a big fan of Wired because their stories have a tabloid pseudo-science feel. This article is a great example. While it says the dealer can't tell with his naked eye, it also says "sophisticated machines designed to help distinguish man-made from mined stones" can. What the actual quality of these diamonds is, the article doesn't say - but rest assured, if a machine can tell the difference, your wife will find out. And no amount of explanation will convince her that a $100 diamond is as good as a$1000 diamond.

Now for the industrial sector, this is a big deal...

7. Dec 29, 2004

### Astronuc

Staff Emeritus
Russ, I agree with you. I don't vouch for Wired or Gemesis.

I am not in the diamond business, and personally, I think crystalline chunks of carbon are over-rated, and way over-priced.

As for the industrial sector, yes, this is a big deal, and its great if Gemesis can reduce the cost and increase quality and quantity for industrial diamond. That is area I would be concerned about.

8. Dec 29, 2004

### omagdon7

Well the fact that the diamonds are produced cheaply in no way suggests they are of low quality. The quality of a diamond gemstones is measured in clarity, carats, cut, and color. Artificially produced diamonds are no different than natural mined gems. And the fact that they are cheaper to produce (they are still sold at the price of natural diamonds) is not a result of anything inherent but a result of the diamond monopoly which artifically holds the price of gems up.

9. Dec 29, 2004

### Will

I don't know where I heard this from (I think it was a physics teacher), but I was told that the reason that a machine can tell the difference is that the man-made ones are "too perfect"

10. Dec 29, 2004

### Gokul43201

Staff Emeritus
Touche'

But the market disagrees. :grumpy:

11. Dec 29, 2004

### thecolor11

The market doesn't have much choice with the DeBeers cartel holding ~90% of the diamond market.

There was a story on one of the network news mags(I think it was 60 Minutes) on these manufactured diamonds. One of the techniques uses nitrogen to accelerate the crystal growth and results in yellow diamonds. There was another technology producing clear diamonds. From what I gathered (this was a while back) diamond fragments were used to start the crystal, and the surrounding carbon simply filled in the crystal lattice.

DeBeers claims they have a machine that can detect the manufactured diamonds using x-rays. Not really sure how that would work. Because they can't run every diamond through these machines, they are starting to laser engrave the DeBeers logo on their diamonds.

Last edited: Dec 29, 2004
12. Dec 30, 2004

### Dayle Record

I can vouch for PBS and the Nova I saw on these diamonds. And with a gaseous process they can make very nice, sparkly white, and blue diamonds. They had a bit of florescence at first, now that is gone, I think. De Beers was protecting its monopoly by desperately searching for a way to detect the manufactured from the natural, and was coming up with the PR that has to do with natural, eternal, real, etc to keep their market share. From what I saw, the manufactured were truly flawless, and very, very bright, having to do with their affinity for high color spectrum hues. Anyhow, I would take a double sized manufactured diamond, for the same money, oh yes.

13. Jan 1, 2005

### Ivan Seeking

Staff Emeritus
14. Jan 3, 2005

### itsmydamnation

i know the russians back in the 80 where able to make gem quality white diamons. quite interesting why they made them, they wanted to use diamond windows for the guidance systems for the ICBM's , a icbm get launched into space get above it target and releases 10 or so warheads. now what was limiting the weight of the warhead that could be droped was that there"eye" in the war head couldn't with stand the temps so if they made the window of diamond they could have bigger and faster falling nukes. whcih would do more dmg and be harder to hit

15. Jan 4, 2005

### omagdon7

I am not aware if the Russians were actually able to make the diamonds. The professor at UF who developed the diamond making technology and helped found Gemesis said that he got the prototypes for the machines he uses from the Russians and that they never were able to make them work.

16. Jan 8, 2005

### Locrian

This is what I currently do for a living.

I am currently working in microwave enhanced chemical vapor deposited diamond. The company I work for is working with a local university, looking to make the research in thin diamond films they have done profitable. We deal mostly in nitrogen doped nanocrystaline films, though it is easy enough to create microcrystalene films (nitrogen off!) and we have made boron doped films at least once by acident. We could probably make single crystal diamond (the university certainly has), but since that is not in the business plan, I'm not going to be trying anytime soon.

The above posts provide a lot of background information. Needless to say, since starting with Vista, I've learned a lot of particulars. More than I would want to try and type out.

If you want particulars, fire away.

Edited per poster request

Last edited by a moderator: Jan 11, 2005
17. Jan 8, 2005

Perhaps a diamond beam window for the Rubbia reactor

That is interesting since one of the problems with Carlo Rubbia's accelerator-driven reactor is the current lack of a usable window material/design for the proton-beam to shine through into the molten-lead reactor coolant (the pressures/temps are a problem for typical beam windows in this environment). Perhaps a material such a diamond might help (in addition to possibly making the window a honeycomb lattice shape, as Richard Garwin has suggested).

18. Jan 9, 2005

### Locrian

Couple of quick comments about this. From what I understand, whan Apollo diamond first produced their diamonds, they were not distinguishible from natural ones except for extremely expensive spectrometers that the vast, vast majority of jewelers would not have. However, I also understand that there are extremely subtle visual clues that some jewlers might catch. Also, Apollo has worked out deals with GIA to help identify their diamonds. Still, Apollo could very well lead this curve if they so chose and beat these new methods, just as SiC gems (moissanite) learned to beat the double refraction problem. I think apollo has purposefully (and wisely) given up trying to stay ahead of this game; their diamonds will be clearly labled as cultured.

As for whether explanation will convince your wife, I'm not so sure you are right. I do think it is true you aren't going to get away with buying a $300 engagement ring instead of a$2500 one. However, diamonds really are beautiful. If someone were selling cheap man made diamonds that were indestinguishable to the eye from real ones, then when she saw the beauty of what $2500 would get her using that, I doubt she'd hesitate for a second. The big problem facint Apollo is that, after all the research, after all the trouble needed to make a good quality diamond... they aren't nearly as cheap as you'd think. When I tell people I work in diamond growth, their eyes get big and they immediately begin babbling about gem diamonds. I have to politely tell them that I have no interest in that sector, and for very good reason. So in short I think people will buy man made diamonds if they are cheap... but I'm not so sure they are cheap, at least not yet. Go check out Gemesis HTHP diamonds. Definately not cheap. In any case, as everyone here has noted, man made diamond will mean a great deal to industry. Diamond has (as i'm sure you are aware) -Super high thermal conductivity -Super high hardness -Super low coefficient of friction (about like teflon) -Almost no chemical reactivity -Reasonably high melting point (4000 kelvin i think?) -Excellent optical transparency (depending on the doping) Diamonds are naturally excellent insulators, and depening on the doping can be made to be semiconductive or reasonably conductive Some uses for diamonds and diamond films: -High energy radiation detectors (diamond detectors are in the process of being deployed at CERN and medical labs) -Super sensitive chemical detectors -Chemical treatment devices (excellent electrochemical properties) -Cutting tools -Transistors -Protective Coatings (can be layered onto glass) -High energy optical windows -Super high pressure sensors -Biomedical coatings (or any other coating where you want to reduce wear) and many more. Of course, they've only been succesfully employed in a few of those. Some very intruiging challenges are before scientists, and as always thats the fun. If you guys would like, I'll post some pictures of our reactor in action. 19. Jan 9, 2005 ### hitssquad Yes, please. 20. Jan 9, 2005 ### hitssquad Authenticity is popular She might see it as gaudy costume jewelry. I would posit that just as authenticity is the reason people read holy bibles, authenticity is the reason females demand mined diamond, no matter how small or ugly they are compared to manufactured diamonds. As you said yourself, indistinguishable to the eye from real ones. You might be able to write a computer program that produces unlimited amounts of great Bible books, indistinguishable in every way from the real ones, but would anyone care to read your apocryphs? When a typical Bible reader saw the beauty of your infinite-book Bible - downloadable for only$29.95 - you doubt he'd hesitate for a second?

Authenticity trumps quality for some people. Junky old Ferraris are worth hundreds of thousands and even millions of dollars. Googling <authenticated auction>

returns 93,000 hits. Authenticity is popular.

21. Jan 10, 2005

### Locrian

Yes, but man made diamond is authentic diamond. It just didn't require underpaid africans with sub-30 year life expectancies (partly due to the job risk) to mine. Some CVD diamond is actually superior to any known natural diamond; I know the guys at Michigan state are having troubles characterizing their diamond's hardness because there is no natural diamond hard enough to compare it to.

I don't know how much research you've done on the subject, but I've done some weak, but I believe meaningful, research by trolling messageboards devoted to diamond and diamond knock-offs (cubic Z, DLC coated cZ and SiC). There is not just interest in man-made diamond, there is a fervor.

I also speak from a certain experience; my wife has SiC gemstone in her ring and SiC gemstone in her necklace. SiC is an interesting diamond substitute because it is almost identical, but not quite as a gemstone. I've watched people's reactions closely. If you see barriers to man made gemstones, I agree, there are barriers. But if you think there is not a monstrous market for cheap, real diamonds, I believe you are wrong.

Of course, the optimal word is cheap. Gemesis' \$4K diamonds don't meet that requirement for me . Time will let us know.

(Couple of pics incoming)

22. Jan 10, 2005

### Locrian

The pics are mostly too big to try and insert into the post, so you'll have to click the links. They are on a little server I pay almost nothing for a month, but its bandwidth should be fine for here.

Just a very quick description of CVD diamond growth so the components make sense:

1) You need a chamber in which the sample is placed, and it must be pumped to a weak vacuum (about 10mT for us) to remove air and contaminants.

2) You then add hydrogen and methane as your primary gases. Other gases can be added to change the properties of the diamond. Examples include nitrogen, boron, argon and others. Some people use acetone instead of methane.

3) This gas is pumped out at a constant rate, so there is always new gas entering and new gas leaving.

4) Now you need an energy source. The energy source has two functions; first, it needs to decompose the methane so you have free carbon floating around. Secondly, your sample must be heated to a high temperature. Diamond (sp3) bonds only form above a certain temperature; below that, you get graphite. Of course, you can't have too high a temperature or you'll melt your sample.

The original energy source (80's) were very hot filaments. Microwave plasma came along about a decade later, but has taken some time to master. There are advantages and disadvantages to both. Ours is a microwave system; you can see the 30kW microwave in the background.

http://www.pitofbabel.org/Vista/GlobalPic.jpg [Broken]

There it is; it was originally operating in the Northeast, Boston area. We had to almost completely rebuild most of the system (we picked it up ourselves, and it came in many pieces). Of course, while stored up there it was subjected to freezing and warming over several cycles. There was extensive damage to the cooling system and I got to be a plumber for about a month :tongue2:

The big silver door held down by bolts is where the sample is inserted into the system. The sample is then raised into the microwave cavity - the black metal section - where the action happens. You can see the small window there where the sample can be viewed when you have a plasma.

http://www.pitofbabel.org/Vista/Plasma007a.jpg [Broken]

For this pic I had turned off the lights. You can see the plasma glowing through the window. It's a small window, so its tough to get good pics of the sample through it.

First, a picture of our sample holder with samples, below:

http://www.pitofbabel.org/Vista/BNHolder.jpg [Broken]

And some pictures with samples added. These are typical square (SPG-422) tungsten carbide 6% cobalt inserts.

http://www.pitofbabel.org/Vista/30Torr-1.jpg [Broken]

http://www.pitofbabel.org/Vista/40samplePlasma.jpg [Broken]

Those are old pics, but frankly they look better than my new ones. The plasma is purple because it is a hydrogen plasma; when methane and nitrogen are added it becomes white. There is a secondary plasma that forms on surfaces and corners and you can see it if you look closely in that second picture.

The actual chemistry that occurs at the surface is extremely complicated (no suprise in a plasma), and there is still ongoing research to discover what actually happens there.

Your substrate is important for good diamond growth. Diamond grows well on most of your M-C carbides (Titanium, Tungsten, Si etc) because of similar lattice structures. Of course, diamond grows best on diamond. Those pictures were taken at about 30torr. Increasing the pressure to 100 or more torr would reduce the size of the plasma but increase the growth rate considerably. That is how single crystal diamond is usually grown on diamond or saphire substrates.

Anyhow, I could certainly go into more, but I'll answer questions if there are any instead of writing a novel.

Last edited by a moderator: May 1, 2017
23. Jan 10, 2005

Barry Bonds, the 1919 World Series, and real good fakes vs the real goods

Then it might seem peculiar that you wrote indistinguishable to the eye from real ones. If the man-made diamonds are the real ones, then which were the real ones that you were referring to before?

As I wrote, authenticity ... no matter how small or ugly they are.

It seems to me that as one of the diamond articles linked here suggested, manufactured diamonds might find much of their market in replacing the small sprinkly diamonds that surround the large centerpiece diamonds in some jewelry. But authentic doesn't have anything to do with structural quality. It often has more to do with where something comes from and when it came from there. And it has directly to do with whether or not recognized authority grants it authenticity. Lists of superior-quality, inauthentic things (Barry Bonds; high-production-value 80's hair metal that was killed by "authentic" but low-production-value indie music; superior-quality copies of decaying art masterpieces; superior-quality copies of the decaying Declaration of Independence; just about any high-quality tailored dress made today vs. Marylin Monroe's Happy-Birthday-Mr.-President dress; just about any of the current Pope's potential replacements vs. the real Pope; etc.) might run endlessly.

If quality is the mark of authenticity, why might anyone be having a problem with Barry Bonds' home-run record?
http://www.abqjournal.com/news/yes/279113yes12-28-04.htm

• But when he breaks Hank Aaron's record, I'd like to see an asterisk by his name: " * used steroids during 2003 season."

"Wow, that's a fabulous engagement ring."

"Oh. Thanks, but it's not real. My fiance cheated and bought me this phony diamond ring. I guess he figured I wouldn't know the difference, but I took it to a top-flight appraiser who managed to identify it as fake since it didn't have the authentic De Beers identifier code that is molecularly stamped on all real diamonds these days. He's such a jerk, but that's why I love him."

24. Jan 10, 2005

### Dayle Record

Locrian, you are generous in your contributions to this thread. I consider Diamonds to be a miracle however they come into being, they are some special carbon. Marketing won't make that any different. We can all shop for what we like, man made are certainly "blood free" diamonds.

25. Jan 10, 2005

### Locrian

That's absolutely right, I should have said natural ones! That's why your later statement "Oh. Thanks, but it's not real. My fiance cheated and bought me this phony diamond ring" isn't correct, because it wouldn't be phony. CVD diamond is perfectly real, it just doesn't require mining first.

I wouldn't feel the need to argue with you - the market will prove one of us right and the other wrong over the next twenty years - except I appreciated you pointing out the obvious mistake, and it leads me into more material worth mentioning.

The primary difference between CVD diamond and natural ones seems to be that CVD is more pure. They've actually used this to characterise them; CVD diamonds can be so pure that they lack natural contaminations you'd expect to find in natural ones. You are right about the small gems, but that is mostly because, due to the time it takes to get these things into production, most CVD diamond growth for gemstones are still using older hot filiament machines. They'll make 1 carat or so, probably not much bigger.

To be honest, exactly how you make CVD diamond to that purity and clarity is a bit of a mystery to me - most likely because I've never had the chance to research it.

Apollo diamond have a rather odd patent, if you look it up. It includes such information as the percentages of certain isotopes of carbon in their methane. I wonder if this isn't just a ploy to get a usable patent though. I do bet they require a much more severe vacuum than we do. If you are trying to eliminate contaminants, I bet a microtorr pressure would be optimal.

Last edited: Jan 10, 2005