What is the Cullinan Diamond?
By Jared James · Last updated 21 May 2026
Definition
The Cullinan Diamond is the largest gem-quality rough diamond ever discovered, weighing 3,106.75 carats when found at the Premier Mine near Pretoria, South Africa, in 1905. It was named after Thomas Cullinan, the owner of the mine. The diamond was gifted to King Edward VII of Britain and cut by the Dutch firm Asscher Brothers into nine major stones and ninety-six smaller ones. The two largest, Cullinan I and Cullinan II, are set in the Royal Sceptre and the Imperial State Crown and remain part of the British Crown Jewels.
Frequently asked questions
- Where is the Cullinan Diamond today?
- The two largest pieces, Cullinan I and Cullinan II, are set in royal regalia and held in the Tower of London as part of the Crown Jewels. Several of the smaller Cullinan diamonds are in the personal collection of the British Royal Family and have been worn as brooches and pendants.
- How much is the Cullinan Diamond worth?
- Because the stones are part of the Crown Jewels and unlikely to ever be sold, they do not have a conventional market price. Cullinan I alone, the largest polished colourless diamond in the world at 530.2 carats, would be worth hundreds of millions of dollars if it were ever valued for sale.
- Who cut the Cullinan Diamond?
- The Asscher Brothers of Amsterdam cut the diamond in 1908. Joseph Asscher, who developed the Asscher cut emerald-cut style, is said to have studied the rough stone for months before making the first cleave. The initial split went exactly as planned and he reportedly fainted from the relief.
Designing a ring
Talk through cullinan diamond with us
Tell us what you have in mind, even if it is only a budget and a piece of jewellery type, and we will help you weigh up the options. We reply to every enquiry, usually within one business day.
Contact the studio