I love it!
Only problem I see is that 0.5 carat cremation diamond is $6000 US, and it would be a "waste" of the ashes since they only use a few ounces (~150g) and a human cremated is roughly 5kg.
BUT, if a person is fine with only sending a portion of their loved one to the moon for the super "low price" of $20k, it would only take 75 to break even, but there is room for a WHOLE lot more.