There are a few points I'd like to address:
> Only by carefully restricting the supply has De Beers kept the price of a diamond high.
This was the case a long time ago but not anymore. De beers seems to only have a 37% market share - not enough to control the market. [O]
> Diamonds, however, are not an investment. The market for them is neither liquid nor are they fungible.
Not entirely true. Diamond prices fluctuate and have appreciated in value over time, you just have to be savvy about it like any other investment. It's unfortunate that the markup on lower quality diamonds is so high but its largely due to a lack of knowledge on the consumer side. AKA do your homework and buy/sell from a wholesaler like abemor.com (wink, wink)
> You might want one because it looks pretty or its status symbol to have a “massive rock”, but not because it will store value or appreciate in value.
You can say the same thing about art. Diamonds are collectors items.
To be continued...
[0] = https://www.google.com/search?q=debeers+marketshare&ie=UTF-8...