By Lisa Barrington DUBAI (Reuters) – Natural diamond supply has peaked and will remain stable for the next few decades, the CEO of mining giant De Beers told Reuters on Monday, adding that the industry should see decent medium- to long-term growth. De Beers Group, Anglo American’s diamond business, is one of the world’s leading diamond miners alongside Russia’s Alrosa. “I don’t see a reason to think there will not be decent growth medium- to long-term in the diamond industry … I feel more positive about the future than I have done for a long time,” Bruce Cleaver said on the sidelines of a di…