The Cullinan II, formally designated the Lesser Star of Africa, is a cushion-cut brilliant diamond weighing 317.40 carats, making it the second-largest polished diamond cut from the Cullinan rough and, by most measures, the second-largest colourless faceted diamond in the world. It is a Type IIa stone of exceptional transparency and near-perfect chemical purity, measuring approximately 45.4 × 40.0 × 27.4 millimetres across its 66 facets. Since 1911 it has been mounted in the front band of the Imperial State Crown of the United Kingdom, where it occupies the most visually prominent position in the most frequently worn piece of British regalia. The diamond is on permanent public display at the Jewel House, Tower of London, except on the occasions — most notably the State Opening of Parliament — when the Crown is in ceremonial use.

The Cullinan Rough: Context and Discovery

The Cullinan II cannot be understood in isolation from the extraordinary rough crystal from which it was cleaved. The Cullinan diamond was discovered on 26 January 1905 at the Premier Mine (now Cullinan Mine) in the Gauteng province of what was then the Transvaal Colony, South Africa, by the mine's superintendent Frederick Wells. It weighed 3,106.75 carats — approximately 621 grams — and remains the largest gem-quality rough diamond ever recorded. The crystal was named after Sir Thomas Cullinan, the mine's owner.

The stone was purchased by the Transvaal government in 1907 for £150,000 and presented to King Edward VII as a birthday gift, a gesture laden with political significance in the aftermath of the Second Boer War. The British government, through Prime Minister Sir Henry Campbell-Bannerman, sanctioned the gift as a gesture of reconciliation with the newly self-governing Transvaal. Edward VII accepted it on behalf of the British Crown, and the rough was subsequently transported to Amsterdam — reportedly in a plain parcel by ordinary post, while a decoy stone travelled under heavy guard — to be cut by the firm of Joseph Asscher & Co.

Cutting and Cleaving: Joseph Asscher & Co., 1908

The task of fashioning the Cullinan was entrusted to Joseph Asscher & Co. of Amsterdam, then the world's foremost diamond-cutting house and the firm responsible for cutting the Excelsior Diamond a decade earlier. The lead cutter, Joseph Asscher himself, studied the rough for several months before making the first cleave. The Cullinan presented formidable challenges: it contained internal cleavage planes and stress fractures that had to be mapped with precision before any blade was set. According to well-documented accounts, Asscher fainted after delivering the first blow — though whether from relief or the strain of months of preparation is a matter of record rather than embellishment.

The rough was ultimately cleaved and then sawn and polished into nine principal stones (designated Cullinan I through IX), as well as 96 smaller brilliants and a quantity of polished fragments. The entire cutting process occupied a team of three cutters working approximately eight hours a day for eight months. The nine major stones were retained by the Asscher firm as partial payment for their work, before being purchased by the South African government and subsequently presented to the British Crown.

The Cullinan II was fashioned as a cushion-cut brilliant with 66 facets — a configuration that maximises the play of light across its broad, flat table while preserving as much weight from the original crystal geometry as possible. The choice of a cushion outline, rather than the pear shape used for Cullinan I, reflects both the shape of the rough section from which it was derived and the aesthetic conventions of Edwardian diamond cutting.

Gemmological Properties

The Cullinan II is classified as a Type IIa diamond, the rarest and most chemically pure of the four diamond types recognised by gemmological science. Type IIa diamonds contain no measurable nitrogen impurities in their crystal lattice — nitrogen being the element responsible for the yellow tinting seen in the majority of gem diamonds. As a consequence, Type IIa stones transmit ultraviolet light efficiently and often display a faint blue fluorescence under shortwave UV, a characteristic consistent with the Cullinan II's documented behaviour. Their optical transparency is unmatched among diamond types, and they frequently exhibit the highest possible colourlessness.

The colour of the Cullinan II has been described in historical and contemporary sources as D-equivalent in modern GIA terminology — that is, exceptional colourlessness — though formal grading by an independent laboratory has not been publicly reported, as is customary for stones of this constitutional status. The clarity is likewise described as internally flawless or very nearly so, consistent with the Type IIa classification and with the careful selection of the rough section from which it was derived.

• Weight: 317.40 carats
• Cut: Cushion brilliant, 66 facets
• Dimensions: approximately 45.4 × 40.0 × 27.4 mm
• Type: IIa (nitrogen-free)
• Colour: Colourless (D-equivalent)
• Origin: Premier (Cullinan) Mine, Gauteng, South Africa
• Cut by: Joseph Asscher & Co., Amsterdam, 1908

Setting in the Imperial State Crown

The Cullinan II was incorporated into the Imperial State Crown in 1911, when the Crown was remade by the royal jewellers Garrard & Co. for the coronation of King George V. It is set in the front of the circlet — the lower band of the Crown — in a prominent position that ensures it is visible from the front in virtually every formal portrait and ceremonial image of the Crown. The setting is a closed-back silver mount that reflects light back through the stone, a technique historically used to enhance the brilliance of large diamonds in candlelit or gaslit ceremonial environments.

Directly above the Cullinan II, in the cross pattée at the front of the Crown, sits the so-called Black Prince's Ruby — in fact a large polished red spinel of approximately 170 carats with a documented history stretching back to fourteenth-century Castile. The juxtaposition of these two stones, one of the oldest named gems in the English royal collection and the newest, creates an inadvertent but compelling dialogue between the medieval and modern histories of the Crown. Below the Cullinan II, in the circlet, are set the Stuart Sapphire and a series of smaller diamonds and coloured stones.

The Crown as currently constituted also incorporates the St Edward's Sapphire, set in the cross at the top of the Crown, and the Cullinan IV (105.60 carats) in the circlet, making it the single most concentrated assembly of historically significant gemstones in any working piece of regalia in the world.

Ceremonial Use and Public Display

The Imperial State Crown is worn by the British sovereign at the conclusion of the coronation ceremony, when the monarch processes from Westminster Abbey, and at the State Opening of Parliament each year. It was worn by Queen Elizabeth II at every State Opening of Parliament during her reign, with the exception of years when the ceremony was conducted without the Crown's physical presence. On these occasions the Crown travels in its own carriage in the royal procession, and the Cullinan II is thus one of the very few diamonds of its scale that remains in active ceremonial use rather than resting permanently in a museum vitrine.

For the remainder of the year, the Crown and the Cullinan II are displayed in the Jewel House at the Tower of London, which receives in excess of two million visitors annually. The Jewel House was substantially refurbished in 1994 and again in subsequent years to improve visitor flow and the quality of display lighting, conditions that allow the Cullinan II's extraordinary brilliance to be appreciated under controlled illumination.

Relationship to the Other Cullinan Stones

The nine principal Cullinan diamonds form a coherent family, all sharing the same exceptional Type IIa purity and provenance. The largest, Cullinan I (530.20 carats, pear brilliant, 74 facets), is set in the Sovereign's Sceptre with Cross and is the largest colourless faceted diamond in the world. Together, Cullinan I and II are the centrepieces of the working Crown Jewels. The remaining seven principal stones — Cullinan III through IX — are held by the Crown and have at various times been worn as personal jewellery by members of the royal family, most notably by Queen Mary and Queen Elizabeth II, who wore Cullinan III and IV as a brooch.

The Cullinan Mine continues to produce exceptional diamonds. In 2009 a 507.55-carat rough Type IIa diamond was recovered from the same orebody, and in subsequent years further large stones have emerged, reinforcing the mine's reputation as a source of the world's finest colourless diamonds. None, however, has approached the scale of the 1905 discovery.

Valuation and Insurability

No formal public valuation of the Cullinan II has been published by the British government or the Royal Household, and the Crown Jewels as a whole are considered constitutionally inalienable — they cannot be sold, pledged, or transferred. Independent estimates by auction specialists and gemmological commentators have placed the theoretical value of the Cullinan II in the hundreds of millions of pounds sterling, though such figures are necessarily speculative given that no comparable stone has appeared on the open market. The Cullinan I and II together represent a concentration of diamond value without parallel in any private or institutional collection.

The question of insurability is similarly complex. The Crown Jewels are not insured in the conventional sense; their protection is provided by the physical security of the Tower of London, which has housed the regalia continuously since the reign of Charles II, and by the constitutional framework that renders their disposition a matter of public law rather than private property rights.

Historical and Cultural Significance

The Cullinan II occupies a position in the cultural imagination of the British Commonwealth that transcends its gemmological superlatives. It represents the final and most spectacular chapter in the history of South African diamond discoveries that began at Kimberley in 1867 and transformed both the global gem trade and the political geography of southern Africa. The gift of the Cullinan rough to the Crown was itself a carefully calibrated act of statecraft, and the stones cut from it have served as symbols of imperial continuity and, more recently, of the complex legacies of that era.

Periodic calls from South African commentators and politicians for the repatriation of the Cullinan diamonds have kept these questions in public discourse. The British government's position has consistently been that the stones were a gift freely made by the elected government of the Transvaal and that they form an integral part of the working regalia of the Crown. The debate reflects broader conversations about the provenance of culturally significant objects held in former imperial collections — conversations that show no sign of resolution.

Within the narrower world of gemmology and the diamond trade, the Cullinan II stands as the definitive example of what a Type IIa diamond can be at the extreme upper limit of size and quality: a benchmark against which all other large colourless diamonds are implicitly measured, and a reminder that the earth's capacity for producing objects of surpassing beauty and rarity has not yet been exhausted.

Further Reading

• GIA — Famous Diamonds: The Cullinan
• Historic Royal Palaces — The Crown Jewels, Tower of London