Moissanite engagement rings are known as cheaper alternatives to diamond rings. But these rings stand on their own due to their durability, affordability, and flexibility of molding them into any shape. This is not a fake diamond but a gemstone. If you are looking for a traditional grey moissanite engagement ring, you may want to consider the various diamond alternatives that are available on the market to use as the centerpiece for your engagement ring. An engagement ring does not have to have a diamond as its centerpiece.