Kim Webb told the watch's elderly owner that it was only worth pounds 15 and offered to "take it off her hands", Southampton Crown Court was told. An identical watch presented by the countess to another crew member was auctioned for pounds 20,000 in March this year.
Janice Brennan, for the prosecution, said Mr Webb, who pleaded not guilty to obtaining property by deception, offered to take the pocket watch in exchange for a pounds 35 service on a wristwatch when the owner visited his jeweller's shop in Southampton.
"Mr Webb was not the good Samaritan that he pretended to be," she said. "He had recognised the date on that pocket watch, 15 April 1912. He recognised it the moment he saw it and he knew full well the significance of that date. This was deliberate exploitation of a vulnerable and ignorant old lady."
The watch originally belonged to Countess of Rothes, a Titanic survivor who was said to have been so moved by the bravery of the crew who helped her - Able Seaman Thomas Jones and steward Alfred Crawford - that she gave them her Benson pocket watches.
The case continues today.