De Beers has played the diamond market, it's historical fact, not some conspiracy theory.

South Africa just so happens to have easily accessed extinct volcanos and more importanly, a cheap labor force allowed the De Beers syndicate to out compete others.

Actually, Russian should have the most gold and diamonds, given it has the largest landmass...

And believe it or not, American women will compare the karat weight and size of their wedding rings as a measurement to the worth of their husband, hopefully, proving to the other women that their husband is better than their's by the size of the rock.

Don't laught. It's true.

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Fields of Space

LOGIC, n.
The art of thinking and reasoning in strict accordance with the limitations and incapacities of the human misunderstanding.

In the Year 2525.

"One small step for (a) man. One giant leap for mankind".

If an astronaut doesn't need good grammar, niether does you.

DDT, Removing invisible elves from backyards since 1939.

Well, there's Canada:and space:

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*

Mantle plumes have been theorized to extend to the core, maybe 3000 km deep. Kimberlite pipes are narrow extrusions that probably originate only ~100 km deep.

Quite right - maybe even a bit more than 100 km.

I hadn't picked up on the OP's notion that South Africa is unique in this regard (gold & diamonds). It isn't; both minerals are found elsewhere in a single country, although SA might be unusual in that, for a not-so-big country, it has an inordinate wealth of both.

A company named Apollo makes diamond gems instead of mining them... not just industrial stuff for grinders and such, but gems... distinguishable from the natural ones mainly by the complete absence of impurities/flaws/imperfections.

As far as the De Beers monopoly, they are busy trying to prove that 'natural' diamonds are somehow superior to manufactured ones.

Considering that large perfect diamonds can be made and sold more cheaply than De Beers has been charging, this may become an uphill struggle.

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Keeper of the Jabberwock

THose are made of teeny tiny atoms! And have you priced those lately?
I'm not made of Money! Leave me alone!

Owning a Diamond , will always be in my dreams , and it will stay as a dream.

They're doing a good job so far.

A lot of women scoff at the idea of a "Fake" diamond, even though it's just crushed carbon.

Oh, BTW, I used to sell diamonds.

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Fields of Space

LOGIC, n.
The art of thinking and reasoning in strict accordance with the limitations and incapacities of the human misunderstanding.

In the Year 2525.

"One small step for (a) man. One giant leap for mankind".

If an astronaut doesn't need good grammar, niether does you.

DDT, Removing invisible elves from backyards since 1939.

Then you are aware of the term "keystone".

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

The slogan "diamonds are forever" is also not accurate.

The diamond allotrope of carbon is unstable at surface conditions and will slowly revert to graphite. Might take a while, so don't toss them out just yet.

I'm not convinced by that, this quote ;

".. Kimberlite pipes are believed to be the remains of magma plugs that have been forced up to the Earth's surface, and there are known Kimberlite pipes with diameters up to a kilometer. There is evidence that in some cases the magma plugs may derive from *mantle plumes...."

was from the site I linked to, and I had heard the mantle plume/kimberlite pipe link before, rather than learning it from that site. (possibly Richard Fortey's 'The Earth' ?)



There was also this bit about meteorites "... Diamonds have also been found in meteorites as microcrystalline clumps up to approximately a millimeter in size, the meteoritic diamonds evidently formed from graphite nodules as *iron meteorites were subjected to intense high pressures by the shock of impact on the surface of the Earth (shock metamorphism)...."

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Life is its own god.

Can you please ask the voices in your head to keep the noise down?

Although having skim read this link http://petrology.oxfordjournals.org/.../full/47/3/631
it appears that kimberlite pipes are created from the upper sections of mantle plumes so hhEb09'1 is right as well.

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Life is its own god.

Can you please ask the voices in your head to keep the noise down?

I' ve been having a long running debate with my wife about "real" vs. man-made diamonds. My position is that if they are chemically identical, then they are the same material, and it should make no difference which one is used to make jewery.

I can talk until I am blue in the face because she knows the difference. The "real" diamonds are mined, and the "fake" diamonds are manufactored!

Got to hand it to De Beers and others running the World's diamond industry; Joseph Goebbels would be proud!

As a solid-state chemist, who has even grown crystals of semi-precious stones (amtheyst in particular), I would agree with your position.

I had a roommate in grad school who's Dad owned a large chain of jewelry stores. I remember discussing once with him how they distinguished synthetic gemstones from natural. He said there were particular tests you could do for particular gems, but generally, the synthetic ones are more perfect (fewer crystallographic defects).

As someone who has been married for almost 18 years, I know you are not going to convince your wife.

One exception to the wife-rule: my wife does have an amethyst necklace made from a crystal I grew. I guess that synthetic are ok if you can say "my husband made the stone".

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At night the stars put on a show for free (Carole King)

I think the prevailing theory back when I was in geology school (early '90s) was that kimberlite pipes were not associated with plumes, or at least we weren't sure enough to say. But it seems that may not be correct anymore. I read the petrology journal article you linked and it does indeed seem to attribute some connection to "ascending mantle flow". Not sure if that means the gigantic plumes which originate from the mantle core boundary, but it may. There is (may be) non-plume mantle movement as well; mantle gyres, I think they're called. If the ascending 'legs' of these gyres are under a craton, they would tend to create the extensional regime (continent trying to pull apart) that is necessary for kimberlite intrusion. Or maybe I'm completely wrong and should go back to using Wikipedia as a sole source of information rather than relying on my faulty memory.

But I don't think we have a real good picture of mantle dynamics yet.

I've got a large sledge hammer, a hot temper and some graphite. Gettin' ideas...

I'd agree with that, most of my geology was learnt in the late '70s, one of my text-books still had mountains forming from subsiding geosynclines!

I had a look at Richard Fortey's 'The Earth' last night and that section is full of 'it appears that' and 'it is believed that'.
I think there is a problem with diamonds forming 150km+ below the crust so mantle plumes are the only mechanism capable of lifting them to/towards the surface, but you are right in saying they wouldn't be formed where the mantle plumes form.

As diamonds go I'd like this one...
http://news.bbc.co.uk/1/hi/sci/tech/3492919.stm (38kb) (although it would devalue the market a little).

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Life is its own god.

Can you please ask the voices in your head to keep the noise down?

Africa has all sorts of interesting minerealogical features - there is that natural nuclear reactor from the high-grade uranium deposits. I think I heard that Africa is also the sole source of certain rare elements like irridium and niobium - apparently asteroidal elements that only crashed there.

Also, since gold was the currency of choice throughout most of history across Asia and Europe, and Asian/European civilization didn't have much overland contact with southern Africa due to the Sahara desert, much of the easy to get gold deposits in Asia and Europe were probably mined out over the course of thousands of years. India had quite a lot of gold stuff. So did China and Korea. Maybe Africa is just unusual in that we hadn't started mining it until recently.

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http://amssolarempire.blogspot.com

Reading this thread got me interested in finding some information on the De Beers company and man-made diamonds. I found this very interesting six page article that chronicles some of the battles that are being fought between De Beers and two high tech companies that are manufactoring diamonds. The last part that talks about the technology behind Apollo Diamonds and the examination of their diamonds by a diamond expert who sides with De Beers is amazing.


http://www.wired.com/wired/archive/11.09/diamond.html