A pair of glasses worn by former Beatle John Lennon have sparked a bidding war after being offered for sale online.
The so-called 'granny glasses' became Lennon's trademark
The trademark circular sunglasses were worn by Lennon during the Beatles' 1966 tour of Japan, where the band played some of their last ever live dates.
Anonymous rival bidders have already pushed the price as high as £750,000 at online auction house 991.com.
"The interest has been phenomenal," said sales director John Warner. "Our phones have been in meltdown."
"It's almost impossible to put a value on them," he added. "They're the rarest of the rare."
Lennon wore the gold-rimmed glasses when the Beatles played five dates in Tokyo's Budokan hall in June 1966.
The band were subject to a high security operation after receiving threats on their lives from religious fanatics angry at the decision to let them play at the sacred site of Budokan.
They were forced to remain virtual prisoners in their Tokyo hotel, with only their photographer friend Bob Whitaker and a local translator, Junishi Yore, for company.
During the stay, Lennon struck up a friendship with Yore and - after the Beatles' final concert - they exchanged gifts in the Japanese tradition.
The glasses were given to the Beatles' Japanese translator
The interpreter, who later became a television producer, presented the Beatle with a set of traditional copper cups; Lennon donated a pair of his sunglasses.
In a handwritten note from 1984, when he parted company with the gift, Yore describes how, as a mark of respect, he removed the black lenses with his thumb on the day that Lennon was shot dead outside his New York apartment in 1980.
"I/we feel he see (sic) us after death in Japan," he explained.
"An item like this comes up so infrequently that it's impossible to predict how high the bidding will go," said Mr Warner, who revealed the glasses had come to the auction site from an American collector.
"We are anticipating huge interest from all over the world, both from institutions and private collectors, especially in the USA and Japan."
Bidding is open until 31 July, 2007.