Dear student,
Platinum is a metal which is heavier and denser than other metals . It is one of the rarest metal on the earth. Platinum is a versatile metal with highest melting point. Platinum has a smooth lustre and also it could be mixed with other metals, which adds an advantage for making of jewellery.It has an excellent value because of its inherent qualities: its purity, strength, durability and its rarity. One ounce of platinum one requires at least ten tons of ore to be processed.
On the other hand,diamond is the hardest substance in earth's existence. It is not malleable, non ductile and non viscous. Therefore, it cannot be moulded or stretched. It is not very reactive and is very brittle.The quality of a finished diamond is determined by: Clarity, Colour, Cut and Carat weight. A diamonds value is often affected by the rarity of one or more of the four C’s.
Due to above reasons Platinum is more precious than diamond.
Regards.