It is Simple, yet Secure
Being strictly functional, claws forego ostentation and simply do what they are meant to: hold the diamond in place. With fewer claws, the security of the stone gets compromised. Four claws are the standard for holding up a diamond safely.
It Compliments the Stone Shape
Imagine wearing a square princess cut diamond. With a claw setting, you will need to decide on the number of claws needed. However, this can be based on the shape of the stone alone. A princess cut diamond usually needs four claws to hold it.
It Lets Light Enter the Diamond
Claws do not restrict the exposure of the stone they are holding, leaving them open so that light passes through freely. This way, more light is refracted through the stone and it sparkles much better than in other settings. The brilliance of your diamond is not diminished in any way.