What is the Oppenheimer Diamond?
By Jared James · Last updated 21 May 2026
Definition
The Oppenheimer Diamond is a 253.7-carat yellow diamond discovered in South Africa in 1964 and named in honour of Sir Ernest Oppenheimer, the long-serving chairman of De Beers who shaped the modern diamond industry. It is one of the largest gem-quality yellow diamonds ever found and is notable for being left in its rough, uncut state, preserving its natural octahedral crystal form. It is held in the Smithsonian Institution's National Museum of Natural History in Washington, D.C.
Frequently asked questions
- Is the Oppenheimer Diamond cut?
- No, the Oppenheimer Diamond was never faceted. It remains in its natural rough octahedral crystal form, which makes it unusual and valuable as a specimen, since most diamonds of its size would be cut into polished gems.
- Where is the Oppenheimer Diamond now?
- It is on permanent display at the Smithsonian Institution's National Museum of Natural History in Washington, D.C., alongside other famous diamonds including the Hope Diamond.
- Who was the diamond named after?
- It was named after Sir Ernest Oppenheimer, the South African mining magnate and long-time chairman of De Beers and Anglo American, who dominated the global diamond trade during the first half of the 20th century.
Designing a ring
Talk through oppenheimer 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