Ask a Tiffany Diamond ExpertTiffany Diamond Experts can assist you in choosing an engagement ring, personalizing a wedding band or selecting a special anniversary gift.Book an In-store AppointmentBook a Virtual AppointmentFrequently Asked QuestionsWhat is a diamond?A diamond is a stone formed from the element carbon. Under high temperature and pressure, atoms form a crystal structure called a diamond cubic.Are diamonds rare?Formed up to three billion years ago below the surface of the earth, diamonds are a miracle of nature. Of the limited number of gem-grade diamonds in the world, only 0.04% meet our exacting standards. For every 10,000 rough diamonds we evaluate, only four will make the cut.What are the 4Cs?Cut, clarity, color and carat weight make up the 4Cs.What makes a Tiffany & Co. diamond?A diamond's quality depends on a combination of the 4Cs—color, clarity, cut and carat weight. However, Tiffany & Co. believes the most critical of these is diamond cut. More than any other fact...