It had sat unnoticed in storage for almost half a century after being mistaken for a work by the little-known, and non-existent, artist Gemmaux.
But a closer inspection of the glasswork at Indiana's Evansville Museum revealed the telltale signs of a 20th century European master. The bold lines, the nod to an earlier cubist aesthetic, the simultaneous use of full face and profile – the clues were all there.
As was the signature, scrawled quite clearly in the top right corner and missed for 49 years following a cataloguing error.
Now correctly identified, museum chiefs look set to cash in on their find, with Picasso's Seated Woman with Red Hat set to go under the hammer in New York, it was announced this week.
Its hoped-for sale price has not been revealed. But it is expected to raise more excitement in the art world than it would have done under the less recognisable name of Gemmaux.
The fictitious artist was the result of a cataloguing error after the work was gifted to Evansville Museum in 1963 by industrial designer Raymond Loewy.
Described in documents as a "Gemmaux", the word refers not to any name, but to the plural of "gemmail" – a medium used to assemble pieces of glass, which when illuminated from behind show their true colours.
Picasso is thought to have been introduced to the form by his friend Jean Cocteau in the early 1950s. He produced around 50 gemmaux pieces during a two year period while studying in France, it is thought.
Unaware of the its true creator, museum staff placed the "Gemmaux" in storage.
And it stayed hidden to the public until New York auctioneer Guernsey's contacted the Evansville centre earlier this year as part of its research into Picasso's gemmaux works.
It was then that museum staff finally became aware of the gem they had in the midst.
"It sparkles like a jewel," said John Streetman, executive director of the Evansville Museum.
He added: "It was undoubtedly a unique set of circumstances that uncovered this treasure within our museum."
But due to the expense of having to display, preserve and protect the piece from thieves, the museum's trustees have opted to hand over Seated Woman with Red Hat to Guernsey's to sell on the open market.
"Now that we have a full understanding of the requirements and additional expenses to display, secure, preserve and insure the piece, it is clear those additional costs would place a prohibitive financial burden on the museum," said Steve Krohn, president of the museum's board of trustees.
[Pablo Picasso graffiti via Shutterstock]