Cursed Amethyst

The heavy steel door of the room known as "the vault" protects some of the museum's most valuable treasures: a Martian meteorite, a rare crystallized gold nugget, and one of the world's largest uncut emeralds. Within this, there is a gem with a dark side.
Ever since it was stolen out of India during the Rebellion of 1857, this amethyst has brought its owners nothing but despair and devastation. It was then known as the Cursed Amethyst. Its last owner had it locked away within seven different boxes in a bank safe, where it was not to be removed until three years after his death.
Colonel W. Ferris is said to have brought the amethyst to England after it was stolen out of the Temple of Indra in Kanpur. Yet the beautiful violet stone’s sinister nature was soon manifested when he lost just about everything he owned and his health deteriorated. The same misery happened to his son who inherited the stone, so he gave it to a friend who subsequently committed suicide. In an unsettling twist, that friend had willed the stone back to the son, now knowing the stone was a deadly account.
In 1890, Edward Heron-Allen received the stone. Yet he soon found himself rattled by a series of disasters.
Desperate to be rid of the thing, Heron-Allen tossed it into Regent’s Canal. Yet three months later, after having been rescued from the depths by a dredger, a dealer gave it back to him. Heron-Allen declared the amethyst: “cursed and stained with blood” and he had it secreted away in his bank vault within seven locked boxes.
Three years after his death in 1943, as he’d instructed, his daughter unlocked the amethyst and gave it to the museum. The amethyst went on display in the Natural History Museum in 2007, set within a ring of silver with two scarab beetle beads decorating one end. Yet some believe the curse has yet to fade.