Discovery of the Cullinan Diamond

Date: January 26, 1905 • Location: Cullinan, South Africa

The world's largest diamond ever, the Cullinan, which weighs 3,106.75 carats (0.621350 kg), is found at the Premier Mine near Pretoria in South Africa.

Diamond is a mineral form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Diamond is a tasteless, odorless, strong, brittle solid, a poor conductor of electricity, colorless in pure form, and insoluble in water. Another solid form of carbon known as graphite is the chemically stable form of carbon at room temperature and pressure, but diamond is metastable and converts to it at a negligible rate under those conditions. Diamond has the highest hardness and thermal conductivity of any natural material, properties that are used in major industrial applications such as cutting and polishing tools.