Sorry Hibud; but there is just NO WAY this will happen.
Chromium oxide (Cr2O3) will always consist in 2:3 "Cr" to "O"
There is no Hydrogen in it (except for impurities that we would have to leave out or it would unnescessarily get waaaaay too deep)
So you can be 100% sure in Chromiumoxid you will ALWAYS have
40% Chromium
and 60% Oxygen
Trust me, I know

This isnīt that deep in chemistray at all.
Chromium oxide forms crystalls. These crystalls consist of many Cr2O3īs
no single Oīs or Crīs.
Solidly bond Cr2O3īs

The easyest way to say this for everybody:
The size of chromium oxide is just as variable as this of diamond and aluminiumoxide.
All of them are availiable in nearly any particle size.
But Cr2O3 is just harder to find in specific sizes.