Here is a photo of a modern replica (Made by Uberti) of a Colt Navy:
Can't get my images to come in. Google Colt Navy and go to "images." Sorry about that.
True, this is a brand new gun, but notice the proportions of the cylinder to the frame, the curve of the hammer, and the flare at the backstrap. this replica has brass trigger guard and backstrap, while the original Navey usually had steel parts.
Hope this helps.