The length-to-width ratio of an oval diamond affects its overall shape and how it will appear on the hand. A classic oval shape usually has a length-to-width ratio between 1.30 and 1.50, giving it a balanced look. A higher ratio results in a longer and more slender oval that can create the illusion of greater length to the wearer's fingers, while a lower ratio will produce a shorter, wider oval. The perceived size and appeal of the diamond on the hand can be significantly influenced by this ratio, so it's important to choose a proportion that complements the wearer's hand.