Zohran Mamdani met with King Charles in New York City just hours after he suggested the king return the Koh-i-Noor Diamond to India.
Mamdani shook hands with King Charles III at the 9/11 Memorial & Museum on Wednesday during a wreath-laying ceremony.
Previously, when asked what the democratic socialist mayor would say to the king, Mamdani told reporters that he would demand one of the most famous British Crown Jewels be returned.
'If I were to speak to the king separately from that, I would probably encourage him to return the Koh-i-Noor Diamond,' he said.
Mamdani's unrelated press conference was held just hours before he was set to meet with King Charles and Queen Camilla.
The ceremony is part of the couple's four-day trip to the US, during which they will honor the 3,000 New Yorkers who were killed during the terrorist attacks of 9/11.
The British monarch has not visited the US in almost 20 years.
The Koh-i-Noor diamond has been a point of contention between India and England for many years. The Asian country claimed it was found in the Andhra Pradesh region.
Mamdani shook hands with King Charles III just hours after demanding he return the Koh-i-Noor Diamond to India
The Koh-i-Noor diamond was acquired by Britain in the mid-1800s
It is a 105.6 carat diamond currently set in the Crown of Queen Elizabeth the Queen Mother, after ending up in the crown jewels in the 1800s.
The infamous gem is on display at the Tower of London. Critics have said that Koh-i-Noor is a 'symbol of conquest,' reported the New York Post.
Mamdani's mother was born in India before she moved to the US for college. The country was under British rule between 1858 and 1947.
The mayor appeared to have taken a frosty approach to the royal visit, Politico reported, much in opposition to President Trump's meeting with the king.
When asked directly again about what he may discuss with King Charles, Mamdani omitted his name altogether.
'I'll be attending a wreath laying alongside other elected officials, including Governor Hochul, Governor Sherrill, and the focus of that wreath laying is to honor the more than 3,000 New Yorkers who were killed in the horrific terror attacks of September 11,' he said.
'And that is really what I'm looking to do at that event.'
Despite Mamdani's cold shoulder, the men were seen talking and smiling at the wreath-laying event on Wednesday.
King Charles III and Queen Camilla laid a bouquet of white flowers at the 9/11 memorial
Mamdani appeared to have a slightly frostier approach to meeting the king than President Trump before him
It is unclear what they discussed and whether Mamdani truly demanded the king return the precious jewel.
King Charles and Queen Camilla laid a bouquet of White Roses on the memorial, which was erected in 2014.
The couple also met with the families of the terror attack's victims. Their visit marks the first by a British monarch since the monument opened.
This is a developing story. Check back for updates.