FLORENCE, Italy — Four years ago, a Florentine restorer happened upon a painting fragment peeking out of an envelope stored in a depository at the city’s famed museum, the Uffizi Gallery. It depicted part of a six of spades.

“I used to play cards with my dad and his friends,” the restorer, Daniela Lippi, 49, recalled. “That small detail meant something to me right away.”

The piece was from “The Card Players” by Bartolomeo Manfredi, an early 17th-century follower of Caravaggio. The painting had been shredded in a 1993 Mafia bombing in the center of Florence that damaged hundreds of art works at the Uffizi. It had been deemed unrestorable. The 615 canvas scraps that could be recovered had been set aside.

On Saturday, after months of crowdfunding efforts in Florence, and 10 months of arduous restoration by Ms. Lippi, the painting will be displayed at the Uffizi for the first time since that attack, which killed five residents and wounded dozens, in addition to damaging historic buildings. It is the last of the damaged works to be restored.