Gold has several different types of karats. They are 10k, 14k, 18k, 22k & 24k. They basically describe the content of Gold in each array of articles.
Platinum is comprised of different elements. Typically they only run as 900 PT and 950PT and has a silver metallic luster.
Diamonds, unlike Gold is as you already know a precious stone. With that said, there are many different characteristics of diamond. Mainly Clarity, Cut, Carat and Color, which are also known as the Four C's. Unlike other establishments, we are diamond gemologist trained with years of experience as well as accredited by the Gemological Institute of America (GIA).