A compulsive gambler committed a "mean and nasty" burglary at the home of his friends.
Ahmed Amijee (19), who had previously baby-sat for the family, secretly took a spare key to get a copy made.
He then waited until they went on a trip and helped himself to £3,000 of jewellery. He sold it for £1,500 – and gambled it all on roulette and blackjack in a casino.
At Leicester Crown Court on Friday, Amijee was sentenced to 12 months' detention.
Neil Bannister, prosecuting, said Amijee let himself into the house in Normanton Road, off East Park Road, Leicester, using the copied key on October 25 last year. A neighbour spotted him on the premises and phoned the mother-of-three who lived at the house.
Amijee spoke to the woman, on the neighbour's phone, and falsely claimed he had been walking past, seen the front door was open and had gone inside to check.
Mr Bannister said Amijee was a friend of the woman's husband and son, and the family had given him work experience as a plumber's mate.
Mr Bannister said: "The day after returning home she realised a bracelet with two diamonds, a necklace and a gold bangle were missing.
"They had belonged to her now deceased mother and were of great sentimental value."
Amijee, of Fairfield Street, Spinney Hills, Leicester, pleaded guilty to the burglary.
The court heard he had been given a police caution for an almost identical offence on Christmas Day in 2011, after he stole house keys from another friend's mother.
On that occasion, he entered the home in St Saviour's Road, North Evington, Leicester, and took a laptop, money box, two mobile phones and a watch. The laptop and one of the mobiles were recovered.
One of Amijee's brothers personally compensated the victims with £400 for the missing watch and a phone.
The brother had also given £1,500 to the victim from Normanton Road who lost the jewellery, by way of compensation, and the defendant had personally apologised, said Nadine Khan, mitigating.
Ms Khan added that her client "regrets what happened and knows he shouldn't have done it".
"Although the offence was planned, it was because of a compulsive gambling habit," she said.
"It began with gaming machines and got out of control.
"He's now stopped gambling. He feels he's brought shame on his family."
Judge Ebraham Mooncey said the offence was "mean and nasty".
He said: "You were a friend of the victim's son and also baby-sat for the family.
"When a neighbour confronted you, you had the gall and nerve to say you were being a good samaritan, having seen the door was open.
"It was a huge breach of trust."
