The Cullinan IV is a 63.60-carat cushion-cut diamond, one of the nine principal stones cut from the 3,106-carat Cullinan diamond, the largest gem-quality rough diamond ever found, recovered at the Premier Mine near Pretoria, South Africa, on 26 January 1905. The Cullinan IV is the smaller of the two cushion-cut stones from the rough (the larger being the Cullinan II, also called the Second Star of Africa, at 317.4 carats and set in the Imperial State Crown of the United Kingdom). The Cullinan IV has spent its century-plus history in the British royal collection and is among the better-known individual diamonds in the Crown Jewels, with a distinctive role both as a setting in Queen Mary's Crown and as a component of the brooch worn frequently by Queen Elizabeth II.

The cutting of the rough

The Cullinan rough was purchased by the Transvaal Colony government in 1907 for £150,000 and presented to King Edward VII on his sixty-sixth birthday, 9 November 1907, as a gift from the people of the Transvaal in commemoration of his role in the constitutional settlement following the Second Boer War. The king delegated the cutting of the rough to the Asscher Brothers of Amsterdam, the leading diamond-cutting firm of the day, and Joseph Asscher's preliminary study of the stone took several months. The first cleaving stroke, struck in February 1908, broke the rough into two principal pieces. From the larger of these came the Cullinan I (530.2 carats, pear-cut, the Great Star of Africa, set in the Sovereign's Sceptre with Cross); from the smaller came the Cullinan II. Subsequent cleaving and cutting yielded the Cullinan III (94.4 carats, pear-cut), the Cullinan IV (63.6 carats, cushion-cut), and a series of progressively smaller stones - the Cullinan V (18.85 carats, heart-cut) through the Cullinan IX (4.39 carats, pear-cut) - along with ninety-six smaller "chip" stones and a quantity of polishing dust. The total weight of the polished products was about 1,063 carats, a yield of just over one-third of the original rough.

The 1910 settlement

The cut stones were returned to King Edward VII in late 1908, and on his death in 1910 the major stones passed into the Crown Jewels through Queen Mary, consort of George V. The Cullinan I and II were set into the Sovereign's Sceptre and the Imperial State Crown respectively at George V's 1911 coronation, and the Cullinan III and IV were set into the new Queen Mary's Crown for the same occasion. The Cullinan IV took its position at the front cross or near the front of the crown, set in such a way that it could be removed and worn separately - a deliberate decision by Queen Mary, who valued the diamonds and intended to wear them in non-coronation contexts.

The brooch and "Granny's Chips"

The Cullinan III and Cullinan IV were combined by Queen Mary into a brooch in which the Cullinan III hangs as a pear-shaped pendant from the Cullinan IV cushion-cut stone above. The combined brooch is the piece most commonly associated with the two stones in their twentieth- and twenty-first-century use, and Queen Elizabeth II inherited and frequently wore it. Her well-known nickname for the brooch - "Granny's Chips", a deliberate understatement - reflected the queen's habitual deflation of the magnificence of the Crown Jewels. Elizabeth II wore the brooch at numerous state occasions, including state visits, gala dinners, and televised broadcasts; it was prominently visible during her 1953 coronation portrait and on many subsequent occasions through her seventy-year reign.

The 2023 use in Queen Mary's Crown

For the coronation of King Charles III and Queen Camilla on 6 May 2023, Queen Mary's Crown was reused for the consort, marking the first reuse of an existing consort crown in over a century. The Cullinan IV was reset into the crown for the occasion, alongside the Cullinan III and the Cullinan V (a heart-cut stone of 18.85 carats from the same rough), making the 2023 setting one of the most concentrated assemblies of Cullinan-cut stones since 1911. After the coronation the stones were returned to the brooch arrangement and to the secure storage of the Crown Jewels at the Tower of London.

Gemmological character

The Cullinan IV is a near-colourless cushion-cut diamond of exceptional clarity, cut to a classic late-Victorian cushion-cut profile that emphasises the stone's depth and reflects the cutting conventions of the early twentieth century rather than the modern emphasis on light return through brilliant-style faceting. The stone is type IIa - the type that includes the majority of the largest South African diamonds, characterised by very low nitrogen content and consequent very high transparency - which contributes to its outstanding optical character. The Cullinan rough was of type IIa, and the daughter stones inherit this quality.

Place in the canon

The Cullinan IV occupies a place in the canon of great diamonds slightly behind the more famous Cullinan I and II, but ahead of most other named stones in size and significance. Its history is straightforward in the sense that it has remained in the British royal collection since 1908, but its meaning is layered: it is a marker of the Transvaal political settlement, a piece of the largest gem rough ever found, an element of two consort crowns, and a brooch worn by two queens. Its periodic public appearance at state occasions across the twentieth and twenty-first centuries makes it one of the most photographed individual diamonds in existence.