By the power vested in me as a Forum Poster in Good Standing, I grant your request.
You're welcome.
Diamonds are already shared across separate worlds accessed using the same login credentials. You should have already noticed that the count is consistent across worlds... Gain in one, see the increase in the other. Unless we're talking about different logins, or different national servers, in which case I think your request was worth a try, but doomed to fail...