What is the opposite of a diamond?

The opposite of a diamond, in terms of geometry, would be a shape with no sides or vertices, such as a circle or a sphere. Diamonds are known for their sharp edges and distinct points, so a shape without any edges or points would be considered the opposite. Additionally, in terms of material properties, the opposite of a diamond could be a substance that is not hard, transparent, or made of carbon atoms arranged in a crystal lattice structure.