Bague en or gris ornée d’un rubis

Grey gold : Grey gold is obtained by adding silver, manganese and copper in specific ratios to the gold alloy.
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.