We all know that diamonds are rare, yet walk past the glittering windows of Bond Street or around the curve of Place Vendôme and sometimes it seems hard to believe. However, exceptionally large diamonds, of the purest, whitest kind take rarity to another extreme level.

For those lucky enough to view them first hand their draw is visceral and hypnotic; how can something so relatively small and hard emit such colour and life, be so icy white and yet sparkle with such fire?

Sotheby’s Diamonds are lucky enough to have just such a creature – all 102.34 carats of D Flawless gem, a globally significant stone described by the Gemological Institute of America, in a letter dated 8 September 2017, as the “Largest Round Shaped, D colour, Flawless diamond ever graded.” And what does that look like? Open your hand – this stone sits nestled into the cup of your palm, its cool weight a delicious, thrilling pressure, its many facets flashing on the back of your retina.

Add into this intoxicating cocktail of size and flawlessness the additional grading of Type IIA. Thought to be only relevant to diamonds from in the famed mines of Golconda in India, stones from Africa are now being found that match this chemical purity. This stone is pure in the most literal sense; it is just carbon, with no traces of any other element, which gives exceptional optical clarity and, like Golconda diamonds, a legendary transparency.

However, for a stone like this to exist and for its qualities to literally shine the intervention and knowledge of exceptional craftsmen is required. Mined in Botswana it weighed 425.40 carats in the rough. Intense study and mapping by Sotheby’s Diamonds partner Diacore resulted in 25 stones – a process that took over 6 months of careful, painstaking cutting and polishing.

Diacore have form – they have previously cut some legendary gems such as the Millennium Star, the Pink Star and one of the first 100 carat diamonds to be sold at auction, the pear-shaped Star of the Season. Which begs the question, why doesn’t this gemstone have a name?

Whoever buys this stone will understand its significance, from an objective, scientific, gemological point of view but they will undoubtedly have an intense emotional reaction to it. They will love it and be fascinated by it, just like man’s first unexplained obsession with diamonds over 2000 years ago; for that lucky person naming it is quite rightly their privilege.