The Koh-i-Noor: The World’s Most Contested Diamond

Its name means "Mountain of Light," and few objects have caused as much rivalry as the Koh-i-Noor. Once reputed to be the largest diamond on earth, it changed hands through conquest after conquest — Mughal emperors, a Persian invader, Afghan kings, Sikh maharajas — before ending up in the British Crown Jewels. Today four nations claim it, and the diamond has become a symbol of empire itself.

A diamond from the age of empires

The Koh-i-Noor almost certainly came from India’s Golconda region, the same diamond fields that produced the Hope. For centuries it adorned the thrones and turbans of Indian rulers — most spectacularly the Mughals’ jeweled Peacock Throne. Each new conqueror who seized northern India seized the diamond too.

Named by a conqueror

When the Persian ruler Nader Shah sacked Delhi in 1739, he carried off the Peacock Throne and the great diamond with it. Legend says that on first seeing the stone he exclaimed "Koh-i-Noor!" — Mountain of Light — giving it the name it still bears. From Persia it passed to Afghan rulers, and then to Maharaja Ranjit Singh, founder of the Sikh Empire, who prized it above all his treasures.

How Britain acquired it

After the British annexed the Punjab in 1849, the terms of the Treaty of Lahore required the young Maharaja Duleep Singh — then only a child — to hand the Koh-i-Noor to Queen Victoria. It was shipped to London and shown at the Great Exhibition of 1851, where crowds were underwhelmed: by European standards its old Mughal cut looked dull and lifeless.

To brighten it for Western eyes, the stone was recut from about 186 carats to roughly 105.6 — sacrificing nearly 40% of its weight for a flash of brilliance.

Recut for the Crown

Prince Albert ordered the diamond recut into a more brilliant oval. The work, done in 1852, dramatically increased its sparkle but shrank it significantly. It was then set into the crowns of queens consort — worn by Queen Alexandra, Queen Mary, and Queen Elizabeth The Queen Mother. By tradition it is worn only by women, owing to a long-standing superstition that the stone brings misfortune to men who wear it.

The diamond that four countries want back

India, Pakistan, Iran, and Afghanistan have all, at various points, demanded the Koh-i-Noor’s return, each citing its passage through their territory. The British government maintains it was acquired legally under treaty. The dispute has never been resolved, making the diamond one of the most politically charged objects in any museum.

Name

"Mountain of Light" (Persian)

Weight

~105.6 carats (recut in 1852)

Origin

Golconda region, India

Set in

Crowns of British queens consort

Home

Tower of London, Crown Jewels

The takeaway

The Koh-i-Noor’s real brilliance is its history. It is less a gemstone than a trophy passed between empires, recut to suit each new owner, and now frozen at the center of a debate about who the past belongs to. Whatever happens next, the Mountain of Light remains the most contested diamond in the world.