Following David Cameron’s comments that there were no plans to return the Koh-i-noor diamond , a group in Mumbai is proposing that India could leas the diamond from Britain rather than it being returned. Similar deals has been proposed in the past for the Parthenon Marbles , where they could return to Greece as a long term loan, to avoid the anti-deaccessioning clauses in the British Msueum act – although, all such proposals have been rejected by the museum.
I do not know what the legal status of the Koh-i-noor is. Unlike the Parthenon Sculptures, it is not held by a museum, but is part of the crown jewels. Now, this is a far more unique situation & I have no idea of the legal framework attached to items such as this belonging to the Crown – so whether any sort of loan is possible without changes in the law is unclear. If anyone knows more about this, please clarify the details for me.
You can vote for the return of the Koh-i-noor on the Made In India website .
Times of India 
‘Kohinoor must be given to India on lease’
TNN | Feb 22, 2013, 03.46 AM IST
MUMBAI: A citizens’ group has provided a unique solution to the tug-of-war over the Kohinoor diamond. It has suggested to the British Prime Minister that the UK government lease it to India for a period of 25 years.
“We do appreciate the safety and preservation that you have offered to the Kohinoor,” a letter from Shailendra Singh, head of Made in India, to British PM David Cameron says, before going on to offer a solution: the British government can lease the Kohinoor back to India for 25 years. The organization had asked Indian citizens to vote for a petition on its website, http://www.iammadeinindia.com, asking for the return of the gem to India.
The Kohinoor diamond ended up with the East India Company in 1849 under the Treaty of Lahore.
“On March 29, 2013, it will be 164 years since the diamond was taken away from us and to date, we await the return of the diamond to its rightful owner, India,” the letter adds.
The organization says it’s aware that the British Museum Act, 1963, prevents national museums from removing items and the UNESCO Convention, 1972, does not cover Kohinoor as part of cultural property that must be restituted.
But these “man-made” laws can’t negate the fact that Kohinoor is an integral part of India’s history and heritage and, therefore, it has come up with the “lease” solution, the letter says.