A version of the classic Brilliant Cut in the shape of a football or a boat.
The physics of light give the greatest results in light performance to the exact Proportions of the Round Brilliant Cut. But all of the brilliant cut variations have an excellent potential for brilliance, scintillation, and fire, if they are cut well.
The longer shapes, of which the marquise is one, because of the unavoidable effects of physics, have a little less brilliance in the center. In poorly cut examples, there is a bow-tie effect, which is less attractive to most viewers. In well cut examples, the bow-tie is very minimal.
Shapes like the marquise are totally a matter of personal taste, so be sure to find out what your loved one prefers, and do not make such choices for a gift without knowing his/her preference.