Everyone knows that diamond market is dominated (and monopolied) by DeBeer & Co. Just Google it out, you'll get a lot of articles...
This is common-place knowledge (and has been long before Google was even invented), so much so that most folks don't waste their breath even saying it. I may as well advise everyone that the Sun will rise tomorrow, and think that I am helping to inform them. There is far more to the fascinating history of diamonds than the existence of De Beers.
I was wondering where you got "DeBeer & Co." from, seeing as I have never heard of them before. So I googled it (google.com.au), and here are the results . Nothing to do with De Beers, and I am not aware that De Beers has ever gone by this name in their 133 year history. Everyone does not know about "DeBeer & Co.", but De Beers is a household name, unlikely to be confused by anybody with diamond knowledge.