One single, sparkling diamond. The solitaire is a classic that will never go out of style. The diamond solitaire engagement ring showcases a single diamond in any one of a variety of settings in a wide range of metals including gold and platinum. They continue to be the most popular choice for engagement rings around the world. They're perfect for women who appreciate understated, classic style but still want to make a bold statement. The solitaire engagement ring can still be as unique as you are, as it accommodates nearly all sizes and shapes of center diamonds.