There must be any number of self-respecting gemmologists out there on first-name terms with other diamonds, but for most of us the Koh-i-Noor is pretty well it. Most of what we think we know might be myth, guesswork or just plain wrong, and yet in spite of — or perhaps because of — that, the diamond which once adorned the Mughal empire’s Peacock Throne still retains all its old, ambiguous allure.

If Anita Anand can trace her own fascination back to a childhood visit with her father to see the stone in the Tower of London, it is rather harder to see just what — other than ‘an ingenious agent’ — might have persuaded William Dalrymple to turn a ‘momentary jeu d’esprit’ into a full-blown book. He is obviously utterly at home with the cultural and historical background to the story, but that doesn’t get round the tricky fact that for the first million years of its history and 60 pages of the book there is absolutely nothing that can be said with any confidence about the Koh-i-Noor.

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While he makes the best of what he has — ancient sacred texts, mighty battles between the ‘invincible bear king’ and ‘beautiful man-god’ Krishna, bejewelled and bare-breasted Indian queens, breathless poets, dazzled visitors, early treatises and pearls, gold, diamonds, spinels and rubies by the shovel-load — it is, as he concedes, a frustrating business. Throughout the early Mughal reigns there are references to stones that may or may not be the Koh-i-Noor, but it is not until 1739, after the sack of Mughal Delhi and the slaughter of 39,000 of its inhabitants, that the ‘Mountain of Light’, gleaming atop the captured Peacock Throne, belatedly emerges into history as part of the vast war booty of the conquering Nader Shah.

Both authors, though, are good story-tellers and from this point on they have a real story to tell. It has to be said that a lot of that story would look much the same with or without the Koh-i-Noor, but for anyone with a taste for that classic blend of blood and bling, for ‘oceans of pearls and gold’ and hecatombs of severed heads, for monstrous heaps of eyeballs — 20,000 of them — and precious stones ‘in quantities that beggar all description’ this is an oriental Game of Thrones — Dalrymple’s own reference — in spades.

In a tale of imperial land-grabs, greed and double-dealing it was probably only a matter of time before Perfidious Albion muscled in; and exactly 100 years after the sack of Delhi its opportunity came. It is an interesting thought that while Nader Shah’s army was destroying a Mughal force of 750,000 men, Britain was still only a bit-player in Indian life. But by the time that the Koh-i-Noor had made its blood-spattered way to Lahore and the sleeve of the old and dying Lion of Punjab, Ranjit Singh, it was a very different India, a different Britain and a different breed of Britons waiting to seize their chance.

Within a decade of the old maharaja’s death the Governor-General, Lord Dalhousie, had not just taken over the Punjab but the Koh-i-Noor with it and was well on the way to turning Lahore’s deposed child-heir into an English country gentleman.

Anita Anand is more than happy to milk the legends and supposed curses that still surround the Koh-i-Noor in its English exile; but it is in the story of the young Duleep Singh’s bathetic descent from prince to drunken Norfolk bore that the more discomfiting questions glimpsed by that six-year-old Anand can be found. She has not forgotten her visit to see the stone, nor her father’s ‘passionate sense of loss’ that the diamond which had once graced the Mughal throne was now, recut and diminished in every way, set into Britain’s Queen Consort’s crown.

Where, though, it should be is another matter. It is not the Elgin Marbles and there is no obvious Parthenon to which it might belong. So where then? India, in whose alluvial sands it was once found? Pakistan, as a demonstration (in Prime Minister Bhutto’s words) of Britain’s ‘willingness to shed its imperial cumbrances’? Iran, which might reasonably stake a claim? Afghanistan, where the Taliban have already demanded its return as an intrinsic part of their cultural heritage? The Sikhs, to whom the Lion of Punjab left it in his will? Or, perhaps — spoils of war again — it should simply be reset in the Pataudi Trophy and fought for every couple of years by England’s and India’s cricketers. A solution, I suspect, that India, at least, would quietly fancy.