The Garrard Cullinan III & IV Brooch is one of the most historically significant pieces of diamond jewellery in the world: a platinum brooch set with the Cullinan III, a pear-shaped diamond of 94.4 carats, and the Cullinan IV, a cushion-cut diamond of 63.6 carats, both polished from the largest gem-quality rough diamond ever found. Created by the London jeweller Garrard & Co. for Queen Mary, consort of King George V, the brooch entered the British Royal Family's personal collection in the early twentieth century and has remained there ever since. Informally known as Granny's Chips — a nickname coined, with characteristic understatement, by Queen Elizabeth II in reference to her grandmother Queen Mary — the piece represents not merely extraordinary gemological rarity but a sustained chapter in the history of the British Crown and its relationship with the diamond trade.

The Cullinan Rough: Discovery and Provenance

The story of the brooch begins on 26 January 1905 at the Premier Mine (now Cullinan Mine) near Pretoria, in what was then the Transvaal Colony of South Africa. Mine superintendent Frederick Wells discovered a translucent blue-white crystal of exceptional size protruding from the mine wall at a depth of approximately eighteen feet. The rough weighed 3,106 carats — roughly the size of a man's fist — and was named after Sir Thomas Cullinan, chairman of the Premier Diamond Mining Company.

The Transvaal government purchased the stone and, in a gesture of political reconciliation following the Second Boer War, presented it to King Edward VII on his sixty-sixth birthday in 1907. The King entrusted the cutting to the Asscher brothers of Amsterdam — Joseph and Abraham Asscher of I.J. Asscher Diamond Company — who had previously cleaved the Excelsior Diamond. After months of study, Joseph Asscher cleaved the Cullinan in February 1908, ultimately yielding nine major polished stones, sixteen smaller brilliants, and approximately 9.5 carats of polished fragments. The two largest stones, Cullinan I (530.2 carats, pear-shaped) and Cullinan II (317.4 carats, cushion-cut), were set into the Sovereign's Sceptre with Cross and the Imperial State Crown respectively, and are held among the Crown Jewels in the Tower of London. The remaining seven major stones — Cullinan III through IX — were retained by the Asscher firm as partial payment for the cutting work, then purchased by the South African government, which in turn presented them to Queen Mary in 1910.

Cullinan III and Cullinan IV: The Stones Themselves

Of the seven stones that came to Queen Mary, the third and fourth are the largest and the most celebrated as a pair.

• Cullinan III weighs 94.4 carats and is fashioned as a pendeloque — a pear-shaped brilliant cut — of exceptional clarity and the characteristic blue-white colour associated with the finest Type IIa diamonds from the Premier Mine. It measures approximately 35 mm in length.
• Cullinan IV weighs 63.6 carats and is cut as a cushion-shaped brilliant, a form that was the dominant cutting style for large diamonds at the beginning of the twentieth century. It shares the same Type IIa classification and optical character as its companion stone.

Both stones belong to the Type IIa category of diamonds — chemically the purest form, containing no detectable nitrogen or boron impurities. Type IIa diamonds transmit ultraviolet light freely, often display exceptional transparency, and constitute a small fraction of all gem diamonds. The Premier Mine has historically produced a disproportionate share of the world's largest Type IIa stones, a geological circumstance attributed to the unusual depth and temperature conditions of the kimberlite pipe from which they originate.

Garrard & Co. and the Making of the Brooch

Garrard & Co., founded in 1735 and appointed Crown Jeweller to the British Royal Family in 1843, was the natural choice to mount Queen Mary's diamonds. The firm's long association with the Crown included responsibility for the maintenance and occasional redesign of the Crown Jewels themselves, and its craftsmen were accustomed to working with stones of exceptional size and value.

The brooch Garrard created for Queen Mary is a model of Edwardian and early-twentieth-century platinum jewellery design: restrained, architecturally precise, and conceived to display the diamonds rather than compete with them. The mount is executed in platinum, the metal that had by the early 1900s largely supplanted silver and white gold in fine diamond jewellery owing to its superior strength, its resistance to tarnish, and its ability to hold stones securely in minimal settings that maximise the play of light. The design allows both the Cullinan III and Cullinan IV to be detached from the brooch and worn independently as pendants — a practical versatility that was characteristic of the finest jewellery of the period and that has ensured the piece's continued relevance across more than a century of royal occasions.

Queen Mary wore the brooch frequently throughout her life, and it became one of the pieces most closely identified with her personal style — a style characterised by magnificent scale and an unapologetic preference for the grandeur of large, important stones worn without excessive surrounding ornament.

Queen Elizabeth II and the Nickname "Granny's Chips"

Queen Mary died in March 1953, shortly before the coronation of her granddaughter Queen Elizabeth II. She bequeathed a substantial portion of her jewellery to the new Queen, and the Cullinan III & IV Brooch passed into Queen Elizabeth II's personal possession — not as part of the Crown Jewels held in trust for the nation, but as private property. This distinction is significant: as a personally owned piece, the brooch has always been available for the Queen to wear at her own discretion, and she did so with notable frequency over the course of her seventy-year reign.

It was Queen Elizabeth II herself who gave the brooch its enduring informal name. Referring to the two great diamonds as Granny's Chips — a characteristically dry allusion to the fact that they were, in a sense, offcuts from the Cullinan rough that had produced the two stones in the Crown Jewels — the Queen's nickname captured both the familial provenance of the piece and a distinctly English habit of deflating the grandiose with the colloquial. The name has since passed into common usage among jewellery historians, auction specialists, and the press, and is now as much a part of the brooch's identity as its formal designation.

Photographs and film records document Queen Elizabeth II wearing the brooch on a wide range of occasions over the decades, including state visits, Commonwealth engagements, and private family events. She wore the Cullinan III alone as a pendant on several occasions, demonstrating the versatility that Garrard had built into the original design. The brooch appears in numerous official portraits and has become one of the most recognisable pieces in the royal collection.

The Brooch in the Context of the Royal Collection

The British Royal Family maintains a distinction between jewels that belong to the Crown — held in trust and not personally owned by the sovereign — and jewels that are personal property, inherited or acquired privately. The Cullinan III & IV Brooch falls firmly in the latter category. It was not acquired with public funds, nor is it among the historic Crown Jewels housed in the Tower of London. It passed from Queen Mary to Queen Elizabeth II by private bequest, and upon Queen Elizabeth II's death in September 2022, it passed to King Charles III and thence, in accordance with the late Queen's wishes, to Queen Camilla.

Queen Camilla wore the brooch at the Coronation of King Charles III on 6 May 2023, a choice that was widely noted as a deliberate act of continuity and tribute to Queen Elizabeth II. The appearance of Granny's Chips at the Coronation — one of the most formally significant occasions in the British calendar — underscored the brooch's status as a piece of living royal history rather than a museum artefact.

Gemological Significance

Beyond their historical associations, the Cullinan III and Cullinan IV are objects of considerable scientific and gemological interest. As Type IIa diamonds of their size, they are essentially without parallel in private or institutional collections. The Gemological Institute of America has documented the rarity of Type IIa diamonds at length: they constitute roughly one to two per cent of all gem diamonds, and examples exceeding fifty carats are extraordinarily uncommon. Both stones would, if they were to appear on the open market, command prices that would set records for any category of jewellery at auction — a hypothetical that has occasionally been raised by commentators but that has no practical relevance given the stones' status as personal royal property.

The cutting of both stones reflects the best practice of the Asscher workshop in the early twentieth century. The pear shape of Cullinan III is a form that demands exceptional skill to execute at large size, as the point of the pear is a structural vulnerability and the proportions must be carefully managed to achieve optical symmetry. The cushion cut of Cullinan IV, while a more forgiving form, was executed with the broad, open facets characteristic of the period — facets that in a stone of this quality and size produce a depth and brilliance that modern brilliant cuts, optimised for smaller stones, do not necessarily replicate.

The Other Cullinan Stones

For context, the remaining major Cullinan stones that came to Queen Mary — Cullinan V through IX — were also mounted in various pieces of jewellery, several of which remain in the royal collection. Cullinan V (18.8 carats, heart-shaped) was set in a platinum brooch that Queen Mary frequently wore at the centre of her bodice. Cullinan VI (11.5 carats, marquise) and Cullinan VIII (6.8 carats, oblong brilliant) were mounted together in a brooch. Cullinan VII (8.8 carats, marquise) was set as a pendant. Cullinan IX (4.4 carats, pear-shaped) was set in a ring. All of these pieces were inherited by Queen Elizabeth II and form part of the same private collection as the Cullinan III & IV Brooch.

Garrard & Co.: A Note on the Maker

Garrard & Co.'s role in the creation of this brooch is inseparable from its significance. The firm's appointment as Crown Jeweller — a position it held from 1843 until 2007, when the Royal Warrant was transferred to G. Collins & Sons — meant that it was responsible not only for creating new royal jewellery but for the care, cleaning, and occasional remodelling of historic pieces. The brooch for Queen Mary was made at a period when Garrard was at the height of its technical and artistic powers, and the quality of the platinum work reflects the firm's mastery of a material that was then still relatively new to fine jewellery. The design's longevity — the brooch has required no significant alteration in over a century of use — is itself a testament to the quality of the original construction.

Further Reading

• GIA Gems & Gemology: The Cullinan Diamond
• GIA Research: Type IIa Diamonds