And police said a hard line would be taken with anyone targeting the elderly - who were sometimes as vulnerable as children.
Mrs Hooper's ring was the last gift she received from her late husband. Wallace, a former journalist, television presenter and game show host, said stealing the ring was like taking candy from a baby.
She told the Herald her mother was unwell after suffering two strokes and powerless to stop the ring being taken.
"We left her ring on because it was so incredibly tight," Wallace said.
"It would have hurt her to get it off, we thought we had no choice."
Wallace's sister Ros Torrance said her mother was unable to speak after her strokes and had little cognitive function.
"She would be physically unable to prevent any theft. It's not the monetary value but the emotional and sentimental value that is important."
Mrs Torrance said the rest home was interviewing staff and reviewing security footage. She had not ruled out making a complaint to police, but would see what the rest home found.
Another Auckland woman whose mother's eternity ring was stolen about nine months ago said her mother had been targeted a number of times since she went into care seven years ago.
"I was incredibly upset about mum's eternity ring disappearing as it wouldn't have been easy to get off," said the woman, who did not want to be named to protect her mother. "The creep would have had to work on this for some time."
Thief preys on 97-year-old in hospital
A 97-year-old woman had her priceless ring stolen from her finger as she lay confused from morphine in an Auckland hospital bed.
Her daughter-in-law, who wanted to be known only as Joy, told the Herald that the heirloom was taken from the elderly woman's ring finger when she was being treated at at an Auckland hospital last week.
"It was her favourite. We visited her the weekend before it was taken and she was telling us how much she loved it. It was given to her by her grandmother, so it's really precious and sentimental to her."
The 97-year-old broke her arm last Monday and was transferred from Elmwood Rest Home, in Manurewa, to the hospital. The next day, her sister-in-law went to visit her in hospital and the thick gold ring set with two rubies and two diamonds was gone. "The strange thing is that she had another two rings on her ring finger which the thieves didn't take."
Joy said her mother-in-law was confused from the morphine and had not realised what happened. "She still doesn't know the ring's gone. She'll be so upset when she's told."
Joy urges whoever stole the ring to return it.
