The watch and the brown leather violin bag belonged to two people who became enshrined in Titanic folklore.
Mr Astor, 47, went down with the ship, after putting his young wife Madeleine into a lifeboat and smoking a last cigarette.
While Wallace Hartley, from Colne in Lancashire, and his eight-piece band famously “played on” to calm passengers as the disaster unfolded around them.
Both items were retrieved when the bodies of their owners were recovered from the water.
“Unlike many timepieces from the Titanic, which are frozen in time on the fateful night, the watch was restored and worn by Mr Astor’s son, Vincent,” said David Beddard, chairman of the British Titanic Society.
“To be able to see J.J. Astor’s watch, knowing it was in his pocket as he put his young, pregnant bride in a lifeboat and stepped back, knowing he wasn’t going to survive, is remarkable,” he added.
