Auctioneers at a Melton sale were taken aback when a lot made 10 times their initial valuation after it was discovered to be 275-years-old.
The minute brass microscope was sold to a Dutch collector for £8,000.
It had been given a cautious estimate of £800 to £1,200 at the latest monthly valuation day at The Samworth Centre in the town.
But that was revised when it was found to have been made in 1743.
Marie Stainton, of the Nottingham-based Mellors and Kirk auction house, which conducted the sale, said: “This was the most talked about item to go under the hammer in the auction, but it was also one of the smallest lots.
“It was a tiny brass simple microscope, so small it could sit in the palm of your hand.
“Our on-the-spot cautious estimate was £800 to £1,200 for the piece.
“But that was made before noticing, almost hidden from view, its early serial number of 16.”
The microscope was put up for auction at the fine art sale at the end of last month.
It may not look particularly impressive to the untrained eye, but its age and historic importance meant it was highly desirable for collectors.
Ms Stainton added: “It may not look much like most people’s idea of a microscope, but in its day it was far from cheap.
“It is, unusually, a combination of brass and silver, the precious metal used for the scale of divisions and nameplate of the maker, which was George Lindsay of London.
“It was intended to be mounted on a stand, and would originally have had a number of accessories.”
Another eye-catching piece at the sale was a 1939 propeller from a Hawker Hurricane aircraft.
It had been bought by the vendor in 1965, and fetched £2,000 in the auction.