There are a number of Diamond's that fought for and against the King. It appears the family came to the New World through Marblehead, Essex County, MA. (Edward Diamond) Possibly with the Palatines from Germany. The Diamond's may have been English soldiers or sailors that brought the Germans over in the 1600's. It appears the Diamonds married into the German group that settled in New York and New England. There are Diamonds listed in Volume II of the Loyalist Directories. However, I know there were Diamond's that fought against the King.
Thanks for the help.