Another alternative is synthetic, lab grown diamonds. They are superior to naturally occuring diamonds, cheaper, aren't tainted by human misery and suffering like conflic/blood diamondst, and arent extracted from ecologically damaging mining techniques like open pit mining.
The prices on these are still artificially inflated. I was told directly by the president of one of these synthetic companies that De Beers will move into large production in a few years For now, the other synthetics are just being allowed to exist as the cartel makes the transition provided they don't undercut too much and stay carefully in a few niches.