Frederick Wells found the Cullinan diamond on 26 January 1905, in the wall of a mine shaft at the Premier Mine in Transvaal, South Africa. He was the mine's superintendent. The stone was at a depth of approximately eighteen feet, glinting in the rock face, and Wells climbed up and dug it out with his penknife.
It weighed 3,106.75 carats. To give that weight a physical reference: a standard golf ball weighs approximately 45 grams; 3,106 carats is approximately 621 grams; the Cullinan, when found, was roughly the size and weight of a large man's fist. It was the largest gem-quality diamond ever found, and it remains so today. Wells was rewarded with a bonus of £3,500.
The stone was named after Sir Thomas Cullinan, the chairman of the Premier Mining Company. What happened to it over the subsequent three years — the negotiations, the transportation, the cutting, the distribution of its nine major pieces — is one of the stranger logistical stories in the history of fine jewellery, and it has produced two of the most significant stones in the British Crown Jewels.
In Brief: Found at 3,106.75 carats in 1905, the Cullinan is the largest gem-quality diamond ever discovered; cut in Amsterdam in 1908, it produced two stones now set in the British Crown Jewels. The account traces the diamond from a South African mine wall through Asscher's Amsterdam workshop to a coronation sceptre.
The Cullinan Stones: Where They Are Today
| Stone | Carat weight | Cut | Current location |
|---|---|---|---|
| Cullinan I — Great Star of Africa | 530.4 cts | Pear-shaped brilliant | Sovereign's Sceptre with Cross, Tower of London |
| Cullinan II — Lesser Star of Africa | 317.4 cts | Cushion-shaped brilliant | Imperial State Crown (front band), Tower of London |
| Cullinan III | 94.4 cts | Pear-shaped | Royal Collection; worn as pendant by Queen Mary and Queen Elizabeth II |
| Cullinan IV | 63.6 cts | Cushion-shaped | Royal Collection; worn as brooch beneath Cullinan III |
| Cullinan V–IX | 18.8–4.4 cts | Various | Set in various pieces of royal jewellery |
The purchase and the problem of getting it to England
The Transvaal government bought the Cullinan in 1907 for £150,000 (approximately £20 million in current terms), with the intention of presenting it to King Edward VII as a birthday gift. The gift was controversial. South Africa was still recovering from the Boer War, the relationship between the Transvaal and the British Crown was complicated, and £150,000 was a significant sum to spend on something that would belong to a foreign king. The gift was debated in the Transvaal parliament. It passed.
The problem then was getting the stone to London. A diamond of this size and value required, presumably, elaborate security: an armoured carriage, a naval escort, a secure vault transfer. What Transvaal officials actually arranged was a decoy. A ship sailed from South Africa carrying a conspicuously secured parcel, attended by detectives and surrounded by rumour. The Cullinan traveled separately, in a plain registered parcel sent by post, with no visible security of any kind. It arrived safely. The decoy arrived safely. Nobody intercepted either.
Edward VII received the Cullinan on his sixty-sixth birthday, 9 November 1907. He was, by accounts, very pleased. The question of what to do with a 3,106-carat diamond was delegated to his jewellers.
Amsterdam, 1908
The Cullinan was sent to Asscher Brothers in Amsterdam, the most respected diamond cutting firm in the world at that time. Joseph Asscher studied the stone for several months before touching it. A diamond of this size was unprecedented, and the cleaving — the initial split — had to be planned with precision. A diamond cleaves along specific planes in its crystal structure; the wrong cut would produce fragments rather than large, workable stones.
The preparation involved making a small groove in the stone with another diamond, inserting a steel blade, and striking it with a mallet. On 10 February 1908, Joseph Asscher made the first blow.
The blade broke.
He struck again. The diamond split perfectly along the intended plane, producing exactly the result months of calculation had predicted. There is a popular account in which Asscher fainted from the tension; there is another in which he did not. Either seems plausible. The room contained one of the most consequential single blows in the history of gem cutting, and whatever the immediate human response was, the result was correct.
The cutting process continued over the following months, producing nine major stones, ninety-six smaller brilliants, and approximately 9.5 carats of polished fragments. The nine major pieces were numbered sequentially from largest to smallest.
The two crowns
Cullinan I, known as the Great Star of Africa, weighs 530.4 carats. It is a pear-shaped brilliant and is the largest colourless polished diamond in the world. It is set at the head of the Sovereign's Sceptre with Cross, part of the British Crown Jewels, and is held in the Tower of London. At the moment of coronation, the Sovereign holds the Sceptre in the right hand.
Cullinan II, known as the Lesser Star of Africa, weighs 317.4 carats. It is a cushion-shaped brilliant and is the second largest colourless polished diamond in the world. It is set at the front of the band of the Imperial State Crown, visible in the photographs of every coronation since George V, immediately below the Black Prince's Ruby. The Imperial State Crown was used at the coronation of King Charles III in 2023, and Cullinan II was in it.
These are, by any measure, astonishing objects. Cullinan I at 530 carats is substantially larger than any diamond that had existed in gem-quality polished form before it, and substantially larger than anything polished since. The size alone would be remarkable. The Cullinan is D-colour and Type IIa: the purest form of diamond chemistry, in which no nitrogen impurities have distorted the crystal structure. Fewer than 2% of all gem diamonds are Type IIa. The Cullinan is the largest Type IIa stone in existence.
Both settings were the responsibility of Garrard, Crown Jeweller from 1843 to 2007 and the firm that handled the integration of the cut stones into the existing regalia after they arrived back from Amsterdam.
Granny's chips
Cullinan III weighs 94.4 carats. Cullinan IV weighs 63.6 carats. Both were given to Queen Mary, who wore them separately and together (III as a pendant, IV as a brooch beneath it), in a combination that became one of the most recognised silhouettes in the history of royal jewellery.
Queen Elizabeth II inherited both stones. She wore them in the same configuration. She referred to them, in private, as Granny's chips. This is a joke that requires knowing what the chips had originally been part of, and in what quantity, and approximately what they were worth, before it is quite as funny as it evidently was to her.
The stones are now part of the Royal Collection and belong to the Crown.
The remaining Cullinan stones (V through IX, ranging from 18.8 carats down to 4.4) are set in various pieces of royal jewellery. Cullinan V is a heart-shaped brilliant set in a brooch. Cullinan VI is in a necklace given to Queen Alexandra. The smaller stones have moved through various settings over the decades and are less consistently documented in public sources than the first four.
What the Cullinan is not
The Cullinan is not the world's most valuable diamond. Coloured diamonds (the Oppenheimer Blue, the Pink Star, the CTF Pink) command significantly higher per-carat prices because their colour is rarer than colourlessness, and because they can be sold, while the Cullinan stones cannot. The Cullinan I and II are Crown property: they are not for sale, have never been for sale, and the question of their valuation is therefore largely theoretical. Estimates exist, but they are exercises in mathematics rather than market assessments.
It is also not, contrary to some accounts, the most perfectly formed diamond ever found. The Cullinan as found had a cleavage surface: a flat, glassy face suggesting it had once been part of a still larger stone. The other piece, if it existed, has never been found. There have been periodic claims that the Excelsior Diamond, found at the same mine in 1893, was a fragment of the same original crystal. The geology of the Premier Mine does not rule this out. It is also not established.
What it is, definitively, is the largest gem-quality diamond crystal ever found. It produced the two largest colourless polished diamonds in the world. It traveled to England in a plain registered parcel, was cut in an Amsterdam workshop in 1908 by a man who had studied it for months and then struck it twice with a mallet, and is now divided between a sceptre and a crown that are taken out of the Tower of London approximately once per generation.
The penknife with which Wells dug it from the mine wall is in the Cullinan mine museum in Cullinan, Gauteng. The mine is still in operation.
Frequently asked questions
How large is the Cullinan diamond?
The Cullinan diamond, as found on 26 January 1905 at the Premier Mine in South Africa, weighed 3,106.75 carats, approximately 621 grams, or roughly the size of a large human fist. It remains the largest gem-quality diamond crystal ever found.
Where is the Cullinan diamond now?
The Cullinan was cut into nine major stones. Cullinan I (530.4 carats, the Great Star of Africa) is set in the Sovereign's Sceptre with Cross, held in the Tower of London as part of the Crown Jewels. Cullinan II (317.4 carats, the Lesser Star of Africa) is set in the band of the Imperial State Crown, also in the Tower of London. Cullinan III and IV belong to the Royal Collection. The smaller stones are set in various pieces of royal jewellery.
Who cut the Cullinan diamond?
The Cullinan was sent to Asscher Brothers in Amsterdam, where Joseph Asscher studied the stone for several months before cutting it. On 10 February 1908, Asscher made the initial cleave, splitting the diamond along its natural crystal plane. The blade broke on the first attempt; the second attempt split the diamond perfectly. Subsequent cutting produced nine major stones, ninety-six smaller brilliants, and approximately 9.5 carats of polished fragments.
How was the Cullinan diamond sent to England?
The Transvaal government arranged a decoy shipment: a conspicuously secured parcel sent by sea with visible detective protection, while the actual Cullinan was sent separately as a plain registered parcel by post, with no visible security. Both arrived safely. It is one of the more successful pieces of misdirection in the history of valuable object transportation.
What is a Type IIa diamond, and why does the Cullinan qualify?
Type IIa diamonds are a rare category of diamond in which the crystal structure contains no detectable nitrogen impurities, producing exceptional transparency and usually D or near-D colour. Fewer than 2% of gem diamonds are Type IIa. The category includes many of the world's most significant stones: the Cullinan, the Koh-i-Noor, the Regent. The Cullinan is the largest Type IIa diamond in existence.
What is the value of the Cullinan diamond?
The Cullinan I and II are Crown property and not for sale, making their market value theoretical rather than established. Estimates based on per-carat values for comparable D-colour, Type IIa diamonds of record size suggest figures in the billions of pounds, but these are mathematical exercises. The stones have never been independently valued for sale and the question of their actual price is unlikely to be answered.
Sources: Ian Balfour, Famous Diamonds (Christie's, 5th ed., 2009); Tower of London Crown Jewels documentation; Royal Collection Trust records on Cullinan III and IV; Premier Mine historical records, Cullinan, Gauteng; GIA documentation on Type IIa diamonds.
