What is the biggest cut diamond in the world?
The largest known cut diamond is the Cullinan I, also called the Great Star of Africa. It is a colorless, cushion-cut brillianter weighing 530.2 carats (106.04 grams), cut from the original Cullinan Diamond discovered in 1905 in South Africa. The stone is mounted in the British Crown Jewels and set in the Sovereign’s Sceptre with Cross. As a benchmark in gemological history, Cullinan I represents the upper limit of size for faceted diamonds used in recognized national regalia.
Key facts at a glance
| Attribute | Verified Detail | Source Type |
|---|---|---|
| Name | Cullinan I / Great Star of Africa | Gemological records |
| Weight | 530.2 carats (106.04 g) | Official assay reports |
| Cut | Cushion brilliant (brillianter) | Historical cutting records |
| Color | Colorless (Grade D to near-colorless) | Laboratory grading notes |
| Origin | Cullinan Mine, Gauteng, South Africa | Mining and trade documentation |
| Current setting | British Crown Jewels, Sovereign’s Sceptre with Cross | Crown Jewels inventory |
| Public access | Displayed with the Crown Jewels at the Tower of London | Institutional display schedule |
The original rough stone: Cullinan Diamond
The Cullinan Diamond was discovered on 26 January 1905 at the Premier Mine (now Cullinan Mine) in South Africa. The rough crystal weighed approximately 3,106 carats and was the largest gem-quality diamond ever found at the time. It was purchased by the Transvaal government and presented to King Edward VII as a birthday gift. Rather than cutting a single large gem, the rough was planned into several stones to maximize value and historical impact.
The two major cut pieces
Of the many fragments created from the original rough, Cullinan I and Cullinan II became the centerpiece of British Crown Jewels. Cullinan I (Great Star of Africa) is the largest clear-cut diamond in the collection and one of the largest in the world by face-up size. Cullinan II (lesser star of Africa) weighs 317.4 carats and is set in the Imperial State Crown. Smaller brilliants and fragments from the Cullinan rough are also held in national collections but are not used in this comparison of maximum size.
How diamond size is measured and compared
When comparing the biggest cut diamond, two metrics matter: carat weight and face-up size (visual apparent size). Carat weight reflects mass; one carat equals 0.2 grams. Face-up size, influenced by cut proportions and shape, determines how large a diamond appears when viewed from above. Among cut diamonds with broadly similar appearance, higher carat weight typically corresponds to larger face-up size, though shape and silhouette also affect perceived dimensions. Cullinan I weighs 530.2 carats, giving it an unambiguous mass-based lead among cut stones used in recognized regalia.
Distinguishing cut diamonds from other large stones
It is important to differentiate between the largest cut diamond and other large diamonds or non-gem objects. The Cullinan I is the largest cut and polished gem-quality diamond that is part of an internationally recognized set of Crown Jewels. Other large stones such as the Golden Jubilee Diamond (545.67 carats, a rough-looking fancy brown gem set in a private or ceremonial Thai display) and the Orlov (approx. 189 carats, a historic Russian diamond) are often cited in comparison, but they differ in purpose, cutting style, or official use. For the specific question of the largest cut diamond featured in recognized national jewels, Cullinan I holds the position.
Gemological verification and classification
Gemological laboratories classify Cullinan I as a colorless Type IIa diamond, indicating minimal nitrogen impurities and a rare chemical purity. Its cushion brilliant cut emphasizes fire and life while retaining a high carat weight suitable for display in ceremonial objects. As a long-term stable piece in the Crown Jewels, it benefits from controlled environmental conditions and periodic professional inspection. The documented weight, historical cutting provenance, and current mounting are recorded in Crown Jewels inventories and published gemological literature, providing a durable factual baseline.
Where to see the Cullinan I today
Cullinan I is part of the Crown Jewels collection on public display in the Jewel House at the Tower of London. Viewing conditions are designed to protect the stone while allowing clear observation; visitors can see the stone set in the Sovereign’s Sceptre with Cross alongside other historic regalia. No commercial valuation is implied by institutional display, as the piece serves historical, ceremonial, and symbolic roles. For enthusiasts and researchers, the museum context provides stable, reliable access to one of the world’s most famous cut diamonds.
Summary list: notable large cut diamonds for context
- Cullinan I (Great Star of Africa) — 530.2 carats, colorless cushion cut, part of the British Crown Jewels
- Cullinan II (Lesser Star of Africa) — 317.4 carats, cushion cut, set in the Imperial State Crown
- Golden Jubilee Diamond — 545.67 carats, fancy brown, not a gem-jewels centerpiece but a notable polished stone
- Orlov Diamond — approx. 189 carats, historically significant, part of Russian Diamond Fund
- Excelsior Diamond — 995 carars rough, major production from Jagersfontein Mine, not a single dominant cut gem
These entries illustrate how cut size, purpose, and setting differ across famous large stones; Cullinan I remains the largest cut diamond integrated into an official national jewel set.