Mosgiel woman Joanna Bishop-Cherry said her mother visited her father Kenneth Bishop's burial site at Green Park Cemetery in Waldronville on Friday, on the fourth anniversary of his death.
She noticed a green-painted, concrete, Maori-style sculpture was broken off and stolen from the top of the gravestone.
It was glued and screwed on, so would have taken tools to remove.
Ms Bishop-Cherry said her mother was "devastated''.
"Mum was just gutted. It's pretty scary, because there's a lot of taonga here.''
The thief likely thought it was valuable greenstone, she said.
"We wanted it because it was pretty - we've always been quite into Maori culture.''
The family just wanted it back and was not interested in punishing anyone.
Ms Bishop-Cherry urged anyone with information about its whereabouts, or who had seen anyone selling the piece, to come forward.
She was told someone saw the sculpture at the cemetery the preceding Tuesday.
It would likely cost thousands to replace including installation costs, she said.
Mr Bishop was a teacher who worked at King's High School for about 20 years, but left a few months before he died of cancer in July 2015.
A police spokeswoman said the police received a report of the incident on Friday.
"At this stage police have no active lines of inquiry. However, we would welcome any information that may assist police in recovering this item.''
