The world’s largest cut diamond is the Cullinan I, also known as the Great Star of Africa, a colorless top pear-cut diamond weighing 530.2 carats. It was fashioned from the original Cullinan Diamond, discovered in 1905 in South Africa and presented to the British Crown Jewels in 1910. The stone is mounted in the Sovereign’s Sceptre with Cross and is regularly displayed in the Royal Collection at the Tower of London. Below is a concise overview of its verified attributes and historical context.
Identity, Weight, and Measurements
Basic Attributes
The Cullinan I holds the record for the largest clear cut diamond in the world by both mass and face-up size. It is a colorless, pear-shaped brilliant with a polished weight of 530.2 carats (106.04 grams). Its dimensions are not always stated in popular summaries, but authoritative sources list an approximate length of 52.40 millimeters, width of 47.40 millimeters, and thickness of 29.70 millimeters. The table below summarizes key verified attributes.
| Attribute | Verified Detail | Source Type |
|---|---|---|
| Name | Cullinan I (Great Star of Africa) | Gemological and historical records |
| Weight | 530.2 carats | Gemological laboratory reports |
| Cut | Pear (brilliant) | Historical cutting records |
| Color | Colorless (grade ranging from D to G in modern terms) | Descriptive analyses |
| Piece of | Original Cullinan Diamond | Historical documentation |
| Current Location | Tower of London, Royal Collection | Institutional custody records |
The Cullinan Diamond Discovery
In January 1905, a surface miner named Thomas Evan Powell discovered a 3,106-carat diamond at the Premier No. 2 mine near Cullinan, Transvaal, in what was then the South African Republic. It remains the largest gem-quality rough diamond ever found. The stone was named after the mine manager, Frederick Cullinan, and sold to the Transvaal government, which subsequently presented it to Britain’s King Edward VII as a symbolic gesture of reconciliation after the Boer War. The rough crystal exhibited exceptional clarity and whiteness, prompting further evaluation and planning for its division.
Cutting and Division Process
The decision on how to cut the Cullinan was debated carefully. It was ultimately entrusted to Joseph Asscher & Co. of Amsterdam, whose family firm had pioneered techniques for cleaving and bruting very large diamonds. The rough was studied for weeks before the cutting plan was finalized. On 26 February 1909, Asscher cleaved the stone into two major parts; these were further subdivided into nine major polished stones and about 96 smaller brilliants. The resulting stones—Cullinan I through Cullinan IX—vary widely in size and use. Cullinan I and Cullinan II are the most prominent, set in British regalia.
Notable Resulting Stones
- Cullinan I (530.2 carats, pear, set in the Sovereign’s Sceptre with Cross)
- Cullinan II (317.4 carats, cushion-cut, set in the Imperial State Crown)
- Cullinan III and IV (minor brilliants used in parures and coronation items)
Ownership, Custody, and Public Access
Cullinan I is part of the British Crown Jewels, a collection held in trust for the nation and managed by the Royal Collection Trust. The stone is typically mounted in the Sovereign’s Sceptre with Cross, a gold rod surmounted by a cross and a dove, symbolizing spiritual and temporal authority. It is regularly displayed to the public when not in use at coronations or state ceremonies. For context, the Cullinan II diamond (317.4 carats) is set in the Imperial State Crown and is also on public view, but Cullinan I remains the largest individual cut stone by weight among Crown Jewels.
Identification and Common Clarifications
Because multiple large Cullinan fragments are displayed in British regalia, confusion sometimes arises about which stone is truly the largest. Cullinan I at 530.2 carats exceeds Cullinan II (317.4 carats), the Koh-i-Noor (approx. 105 carats, historically recut), and other notable historic diamonds. The Cullinan I’s clarity is assessed as internally flawless to very slightly included, with strong white color. Its value is not publicly insured and is not traded, as it is regarded as a national and historic treasure rather than a market gem.
Significance and Legacy
Beyond its size, the Cullinan I represents a milestone in diamond cutting, governance, and cultural heritage. Its journey from a rough crystal in South Africa to a central element of British coronation regalia illustrates the complex interplay of geology, industry, diplomacy, and symbolism. The stone’s careful assessment, division, and integration into symbols of state authority continue to inform how institutions, scholars, and the public understand large diamonds today.
Note: This article uses measurements and weights reported by gemological authorities, museum records, and historic documents. Values are subject to the precision of published sources and may reflect rounding in secondary references.