The Diamond is similar to other cruise ships. On Formal nights, tux or dark suit and a gown for the ladies, on Informal nights, sport coat and tie and perhaps a pants suit, and on casual nights, sport shirt and slacks and similar for the ladies. Forgive me, I am a man and I just don't know the appropriate terms. The Diamond is a nice ship. Not as nice as it was with the female wait staff, but a very comfortable ship with good entertainment and lecture staff. It used ti be our favorite ship of 90+ cruises.