Ruby Zoisite sphere 50 dollars per kilo
A ball with a diameter of 50mm weighs about 0.21kg
A ball with a diameter of 55mm weighs about 0.27kg
A ball with a diameter of 60mm weighs about 0.35kg
A ball with a diameter of 65mm weighs about 0.45kg
A ball with a diameter of 70mm weighs about 0.56kg