Diamonds are primarily made of carbon, a chemical element symbolized by 'C'. In their crystalline form, carbon atoms are arranged in a tetrahedral structure, resulting in the diamond's characteristic hardness and brilliance. This structure not only contributes to diamonds' stunning appearance but also makes them the hardest natural material known. Diamonds are formed deep within the Earth's mantle under extreme pressure and temperature conditions, and they are brought to the surface through volcanic activity. They are highly valued for their use in jewelry and various industrial applications.