The choice of diamond cut is often decided by the original shape of the rough stone, location of internal flaws or inclusions, the preservation of carat weight, and popularity of certain shapes among consumers.
The cutter must consider each of these variables before proceeding.

Having said that, the vast majority of stones used in jewellery these days are

Round brilliant cuts:

This is because of a formula developed at the beginning of the twentieth century designed to maximise the reflectivity of diamond. There will always be some variation, but the same basic proportions are maintained to give the stone maximum ‘sparkle’
Then there are fancy cuts, perhaps not quite so bright but fulfilling many design directions.

Marquise Diamond Engagement Ring

One of our favourites is the marquise or navette (French for “little boat”, because it resembles the hull of a sailboat):

Moi et Toi ring set with two pear diamonds

or indeed the pear cut that does indeed work well in ‘pairs’ such as here in our moi et toi ring that is becoming rather famous!

Princess Cut

This is a really bright square cut that is very popular, particularly in our rub-over settings