When we say cleavage of a diamond we refer to its ability to have smooth surfaces when it is broken down. The breakdown of diamond also occurs in certain definite directions. Cleavage there fore means dividing a diamond crystal into two or more pieces by splitting the stone through the cleavage direction also called its grain. Cleavage in chemical terms basically means the place where the layers of atoms are most weakly bound and can be broken most easily.
Well it do not have any cleavage because the hardness is 10 that is really hard
A diamonds luster
Clear I think
Not sure, but broke one (with pressure) and it might not be a diamond, but it cleaved hexagonal, I think.
I think that all sides have cleavage but do not trust this cause I'm making a wild guess.