Solitaire in platinum decorated with a diamond calibrating about 0.3 carat.

Platinum : Platinum is the most precious metal on earth. unlike gold that is too soft to be used whithout being alloyed with 25% of other metals, platine can be used 95% pure. It extremely white color is appreciated for setting extremely pure diamonds.
Diamond : In mineralogy, diamond is an extremely rare, precious and hard (named after the ancient Greek "unbreakable") metastable allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice.
Carat : The carat (ct) is a unit of mass equal to 2 g. Carat is used for measuring the weight of gemstones.