Glasses raised for pounds 19k.
After a woman bought them at the sale in Portsmouth, Hampshire, she took them to the Stride and Son saleroom in Chichester, Sussex.
Experts there recognised that they were made by revered glassworker William Bielby in Newcastle-upon-Tyne in around 1765.
They bear the coat of arms of John Thomas, a Cumberland vicar, and fewer than 100 are believed to have been made.
Yesterday at the auction house, they went under the hammer for pounds 16,000.
The winning bidder, who deals in glass, paid a total of pounds 18,880 after extra fees were added.