I'm pretty sure Diamond is a special groestl and crackfoo mentioned that he was only getting rejects the last time he tried to add it. Be nice though since it seems to be a pretty profitable coin at times.
I tried to mine it at some pool, got me plenty in the first hour then the difficulty must have changed and I got almost nothing in the next two hours. Guess it's some chinese asic scam like Bitcore... as usual
PS sort of special Diamond-Groestl algo from ccminer/sgminer