During the Edwardian era, marquise cut diamonds were extremely popular and were typically used in ring designs. This diamond cut is similar in shape to a boat (hence its other name ‘navette’ which means boat) with two pointed edges. Marquise diamonds are ideal at slimming and elongating fingers because of their long, elegant shape.
Note that sailing was one of the favorite hobbies of King Edward VII and some speculate that this was a reason the boat-shaped cut was a favorite diamond cut, although this connection might be stretching it a bit.