> because their sales and distribution channels are controlled by a cartel.
...which is only effective because naturally-occurring diamonds are hard for the average person to get. If there could be a water cartel there would be, but it doesn't work because 1) you can just go down to the river/find some snow/dig a well/etc/etc, and 2) water is inefficient to move in large quantities. You could fit millions of dollars worth of diamonds in the space of 1L of water (maybe $10-$100 at cartel prices)
...which is only effective because naturally-occurring diamonds are hard for the average person to get. If there could be a water cartel there would be, but it doesn't work because 1) you can just go down to the river/find some snow/dig a well/etc/etc, and 2) water is inefficient to move in large quantities. You could fit millions of dollars worth of diamonds in the space of 1L of water (maybe $10-$100 at cartel prices)