The Jacob Diamond, also known as the Imperial or Victoria Diamond, is a colourless diamond from India ranked as the fifth-biggest polished diamond in the world. The last nizam of the Hyderabad State, Mir Osman Ali Khan, found the diamond in the toe of the shoe of his father at Chowmahalla Palace and used it as a paperweight for a long time. It was bought by the government of India for an estimated $US13 million in 1995. It is cut in a rectangular cushion-cut, with 58 facets, and measures 39.5 millimetres (1.56 in) long, 29.25 millimetres (1.152 in) wide and 22.5 millimetres (0.89 in) deep. The diamond weighs 184.75 carats. Currently, it is kept at the Reserve Bank of India vaults in Mumbai. As part of the Nizam's jewellery exhibition in 2001 and 2007, the Jacob Diamond was a major attraction at Salar Jung Museum, Hyderabad.

Mir Osman Ali Khan, Asaf Jah VII was the last Nizam (ruler) of the Princely State of Kingdom of Hyderabad, the largest state in British India. He ascended the throne on 29 August 1911, at the age of 25 and ruled the Kingdom of Hyderabad between 1911 and 1948, until India annexed it. He was styled as His Exalted Highness (H.E.H) the Nizam of Hyderabad, and was widely considered one of the world's wealthiest people of all time. With some estimates placing his wealth at 2% of U.S. GDP, his portrait was on the cover of Time magazine in 1937. As a semi-autonomous monarch, he had his mint, printing his currency, the Hyderabadi rupee, and had a private treasury that was said to contain £100 million in gold and silver bullion, and a further £400 million of jewels. The major source of his wealth was the Golconda mines, the only supplier of diamonds in the world at that time. Among them was the Jacob Diamond, valued at some £50 million, and used by the Nizam as a paperweight.