Some 34 years ago Peter Tandy, a young curator at the Natural History Museum, happened upon a jewel while working among the great lines of mineral cabinets. From a scientific perspective, the stone was nothing special, though its setting was rather bizarre, bound by a silver ring decorated with astrological symbols and mystical words with two scarab-carved gems attached. It was a typewritten note that accompanied the jewel, an amethyst known as the Delhi Purple Sapphire, that caught Tandy’s eye.

“This stone is trebly accursed and is stained with the blood, and the dishonour of everyone who has ever owned it,” said the note, which had been written by Edward Heron-Allen, a scientist, friend of Oscar Wilde and the amethyst’s last owner. It carried a curse and had left a trail of bad luck and tragedy.

Heron-Allen claimed to have been so disturbed that he had surrounded the amethyst with supposedly protective charms and sealed it inside seven boxes before leaving it to the museum in his will. His letter concluded: “Whoever shall then open it, shall first read out this warning, and then do as he pleases with the jewel. My advice to him or her is to cast it into the sea.” While they were sceptical, Tandy and his colleagues agreed to keep quiet about the curse.

The jewel might have remained hidden if its remarkable story had not caught the imagination of staff working to relaunch the museum’s public mineral gallery, the Vault. On Wednesday, the Delhi Purple Sapphire will go on permanent display at the museum, complete with a label declaring its reputation as “trebly accursed”.

A supernatural tale might seem to sit a little uneasily in one of the world’s great scientific institutions. But according to Alan Hart, head of collections in the mineralogy department, such narratives give the collection a cultural dimension that appeals to visitors.

“People ascribe precious stones with all sorts of legends. All it needs is for one owner to declare it to be cursed or lucky and the story will remain with the stone as it is passed from person to person through history,” he says.

But that the Delhi Purple Sapphire was cursed was never doubted by Heron-Allen’s family. Ivor Jones, his grandson, a 77-year-old former naval officer, refuses to handle the jewel.

“My mother certainly wouldn’t touch it and she recommended that we didn’t either because of the curse,” he says. Heron-Allen was one of the most remarkable individuals ever associated with the Natural History Museum. Independently wealthy, he trained as a solicitor while simultaneously learning the art of violin-making – his book on the history of the instrument, published in 1884, is still in print. He studied Persian and wrote a prose translation of The Rubaiyat of Omar Khayyam. But it was as a scientist that he forged the strong bond with the museum that would ultimately see the cursed amethyst wind up in South Kensington.

He had a lifelong fascination with foraminifera, single-celled aquatic organisms that create exquisite, shells and by the time he died in 1943 he had already given the museum the world’s finest library of works on the subject.

But later that year a box arrived that nobody had been expecting. The accompanying note, written by Heron-Allen told the story of the Delhi Purple Sapphire. It had, Heron-Allen said, been brought to the UK by a Bengal cavalryman Colonel W Ferris after being looted from the Temple of Indra in Cawnpore – now Kanpur – during the Indian Mutiny in 1857. The soldier thereafter lost money and health, his son doing likewise after inheriting it. A family friend who possessed it for a short time committed suicide.

Heron-Allen was given the stone in 1890 and was immediately beset by misfortunes. He twice gave the stone to friends who had asked for it – one “was thereupon overwhelmed by every possible disaster”, the other, a singer, found “her voice was dead and gone and she has never sung since”.

He even claimed to have thrown the amethyst into Regent’s Canal only for it to be returned to him three months later by a dealer who had bought it from a dredger.

In 1904 he had had enough. He declared: “I feel that it is exerting a baleful influence over my newborn daughter”, had it shipped to his bankers with instructions that it be locked away till after his death. It might sound farfetched but even scientists are not immune to the story’s power. Seven years ago John Whittaker, former head of micropalaeontology at the Natural History Museum, took the amethyst to the first annual symposium of the Heron-Allen Society, an organisation founded to discuss the man’s life.

On the way home, he says, “the sky turned black and we were overtaken by the most horrific thunderstorm I’ve ever experienced. It was so bad we considered abandoning the car and my wife was shouting, ‘Why did you bring that damned thing?’ ” Whittaker was taken violently ill with a stomach bug the night before the second symposium and he missed the third when he developed a kidney stone. The fourth symposium, in 2004, was held at the museum. “We were all a bit apprehensive on the eve of that meeting,” he says.

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