Thieves posing as would-be property buyers stole jewellery from a family during an open home.
The incident in East Auckland has led to warnings from the police and a real estate expert about the need for vigilance and security.
Police spokeswoman Noreen Hegarty said the thieves filled in the viewer register with false names and contact details before ransacking the house.
"It's important that vendors ensure valuables are either removed during the sale period or locked away."
Real Estate Institute of New Zealand chief executive Helen O'Sullivan said the theft was one of only two such cases she had heard of.