NYC Mayor Mamdani encourages King Charles to return Koh-i-Noor diamond. Here's why the jewel is controversial.

New York City Mayor Zohran Mamdani said if he talks to King Charles III during his visit, he would encourage the king to give back a diamond with a long, controversial history.

A jewel called the Koh-i-Noor is contained inside the Crown of Queen Elizabeth. The diamond is believed to have originated from India. It was given to Queen Victoria in 1849 as a condition of the Treaty of Lahore, which ended the first Anglo-Sikh War.

Many Indians believe the diamond still belongs to India and that the British stole it. 

The jewel came up when Mamdani was asked Wednesday about King Charles' visit.

"I would probably encourage him to return the Koh-i-Noor diamond," he said.

What's the significance of the Koh-i-Noor? 

The 105.6-carat jewel is inside a crown given to Queen Elizabeth II's mother in 1937. It's on display at the Tower of London. 

It has had many previous royal owners, including heads of the Mughal Empire, shahs of Iran, emirs of Afghanistan, and Sikh Maharajas, according to the Historic Royal Palaces. 

In 2016, India's Culture Ministry said the government would make every possible effort to get the diamond back.

For many Indians, the loss of the Koh-i-Noor is symbolic of the country's subjugation under colonial rule.  

Pakistan and Afghanistan have also squabbled over who should have the jewel. 

Dr. Amanda Foreman, a royal contributor, said King Charles doesn't own the Koh-i-Noor diamond. The nation owns it.

"The king has no more power to return the diamond than he has to return Buckingham Palace to the people," Foreman said. 

Crown not worn during King Charles' coronation

Queen Camilla was supposed to wear the crown housing the jewel during her husband's coronation ceremony. The stone has been featured in previous coronations.

Camilla wore a modified version of Queen Mary's crown, featuring diamonds from Queen Elizabeth II's personal collection. 

But Camilla did wear the crown with the Koh-i-Noor to the funeral of Queen Elizabeth II in 2022.