[ggm]

Edward Jay Epstein wrote on this in 1982, the de Beers cartel has been propping up natural diamond prices for decades. It's deep in Veblen goods territory.

The Argyle mine stopped digging up pink diamonds, I am pretty sure it's to maintain value of the stocks in circulation and held by the company.

[defrost]

I'm pretty sure Rio tapped out on Argyle as they had worked their way through the entirety of the alluvial deposit after 35+ years of extraction.

They were very keen to find a lode source kimberlite pipe and get more pink diamonds but sadly .. no show (as of the last time I looked at the Tech. Reports on regional exploration).

There was absolutely a financial element on the decision to shutter and rehab the mine site .. but it was driven more by diminishing returns at that deposit than by market starving.

They don't seem to have any plans to reopen as they're supposedly going into full rehab mode (all equipment gone, return to nature):

https://www.riotinto.com/en/operations/australia/argyle

[ggm]

They had a very nice stockpile of investment grade pinks afaik and cashed them in for a while with an annual release. The Web agrees with you, the mine stopped being economically viable. I think I just read 95% of it was bort and so industrial anyway.

https://minedocs.com/26/Discovery-and-Mining-of-the-Argyle-D... is old but fascinating and had great photos and maps.

[defrost]

Heh, your edit (no drama)

> I didn't realise the hunt for the pipe had ended.

Well the hunt for the actual source pipe ended some time back, the thinking being that most if not all of it had been ground down and cast into the giant bank that was the mine .. but hunting for pipes in general never ends - it's an ongoing part of any and all magenetic surveys to flag the distinct peaks of an magnetically aligned Kimberlite pipe.

( ^^ left in for posterity, clearly at odds with your article :-) )

Now reading your article (thanks) I find my recollection of the geology to be at odds with the article .. I was under the foggy recollection that the mine was alluvial - of diamonds that had been broken away from a pipe and banked up in gravel .. the article talks as if it was directly mining an intact pipe .. nope, correction, mining the alluvial deposits from a named pipe ..

Okay - they mined part of the remaining pipe (the remainder wasn't "economically viable) and the gravel deposits downstream.

That makes sense .. I must have an old memory of a missing diamond pipe somewhere else.

And yes, most diamonds found would be industrial grade and not gem grade.

FWiW many diamond pipes are only good for 40 or fifty years if that - what tends to be lost in the details is that some areas of the world have a high number of diamond pipes in close proximity and some mines clean up a few at once or one after the other.

Thanks again for the article, skimmed for now, bookmarked for 'ron.

[ggm]

I was blovating. Exceeded my competency to comment fast.