The Millennium Star is a 203.04-carat pear-shaped diamond, graded D in colour and internally and externally flawless in clarity, cut from a 777-carat rough crystal recovered from the Mbuji-Mayi alluvial diamond fields of the Democratic Republic of Congo (then Zaire) in 1990. The stone is the centrepiece of the De Beers Millennium Jewels collection produced for the year 2000 and remains one of the largest top-colour, top-clarity diamonds ever cut. Its public profile owes equally to the cut itself and to the dramatic, unsuccessful attempted theft of the collection from the Millennium Dome in London in November 2000.

The rough and the planning

The 777-carat rough crystal was an unusually clean piece for a stone of its size and was acquired by De Beers shortly after its recovery from the alluvial workings at Mbuji-Mayi. The Mbuji-Mayi field is one of the world's most prolific alluvial diamond areas and has produced significant quantities of industrial diamond and a smaller but important stream of high-quality gem material since the early twentieth century. The recovery of a piece of this size and quality was a significant event in itself.

Planning the cut occupied De Beers' specialists for more than three years. The work involved both technical analysis of the rough — using laser inspection, computer modelling, and three-dimensional crystallographic analysis — and a series of decisions about whether to maximise weight retention from a single large stone or to subdivide the rough into multiple smaller pieces. The decision to produce a single 203-carat pear-cut stone reflected the assessment that a single large stone of this colour and clarity would have substantially greater individual value and historical significance than any combination of smaller cuts.

The Millennium Jewels collection

The Millennium Star was designed as the centrepiece of a collection of twelve rare blue diamonds — the Millennium Sapphires — and other stones that De Beers assembled to celebrate the turn of the millennium and to mark its position as the dominant force in the diamond trade. The collection was exhibited at the Millennium Dome in London in 2000, displayed in the Money Zone of the exhibition complex.

The 2000 attempted heist

On 7 November 2000, an organised gang of robbers attempted to steal the Millennium Jewels from the Dome using a stolen JCB excavator to crash through the perimeter fence and a smoke-grenade and gas-mask diversion at the display case. The attempt was intercepted by the Metropolitan Police's Flying Squad, who had been informed of the planned robbery in advance through intelligence work and had replaced the actual stones with replicas before the attempt. The would-be robbers were arrested at the scene and subsequently convicted; the actual Millennium Jewels were never at risk. The story has been the subject of multiple book treatments and a 2018 BBC documentary.

Subsequent ownership and exhibition

The Millennium Star has remained in private ownership and has been exhibited periodically at major jewellery exhibitions including the Smithsonian and various international gem shows. The stone has not, to public knowledge, been sold at auction or transferred between major collectors; its status as a De Beers-controlled showpiece has been maintained.

Further reading

• De Beers Group — heritage diamonds
• GIA — major historical and modern diamonds
• GIA Gems & Gemology — notable diamonds