Officers condemned Robert Ziga’s actions after he was jailed for five years and four months at Bradford Crown Court.
Ziga went into 75-year-old Christine Brown’s room in Bradford Royal Infirmary’s cancer ward where she was recovering from a stroke.
She did not have cancer, the court was told yesterday.
He pulled off the diamond ring, which she had worn for 52 years, a judge heard. Ziga also took her telephone. Nurses were alerted by Mrs Brown’s screams.
Ziga, 29, of Manningham, Bradford, admitted the robbery.
Judge Robert Bartfield heard he had been wandering around the wards searching for things to steal.
He fled after the robbery but was caught later and told police where to find the ring so it was returned.
Detective Constable Richard Oxley, of Bradford South CID, said: “This was a heartless and despicable act committed against an elderly patient at her most vulnerable.
“Ziga displayed greed, when most would have shown compassion, inflicting only further strain on his victim’s health.
“With the help of witnesses and CCTV footage, officers worked extremely hard to ensure he was quickly identified and arrested for this offence.
“The sheer audacity of Ziga’s actions have clearly been recognised by the courts and I am pleased to see that this individual will now be removed from our communities for some considerable time.”