Most important with all these shapes is that light
passing through them is properly refracted
in order to give maximum brilliance or sparkle to the diamond.

It is the precision of the cut that determines this sparkle, also
sometimes called the 'life' or 'fire' of the diamond.

When the diamond is cut to good proportions, with scientific established
parameters followed correctly, light will be perfectly refracted
through the facets returning to the eye.

1: perfect cut, very good refraction
2: bad proportions, too thick
3: bad proportions, too shallow