RE:RE:dabard51Anglo in theAnnual Report says that they sell a "majority" of their diamonds the way you describe. These sights or viewings. It is still similar to an auction, in that if the buyer does not bid then the lot would be passed to another buyer and the price may or may not change.
It would be more like a Dutch auctionor reverse auction but a privateone, not with an open outcry. This would probably lead to better realizations but not 100% more, or even 50% more, my guess,5-10% higher prices. I am going to assume that they would do this for some more valuable stones with their best customers.
I assume that the regular run of the mill stones go thru the auction like MPVD does at Bonas.
And then some stones are not sold at all but cut and polished and/or marketed directly by DeBeers.
Anyone with detailed industry knowledge care to comment on DeBeers marketing?
IMO it is certainly much more transparentand less a monoploy or cartel than it used to be years ago. You can not "control" a market with 30% production share if there are tens of other suppliers holding all the rest of production/supply.