Watch: Touching moment man reunited with century old family heirloom after it was found in Rarotonga

An Auckland man has been reunited with a long lost century-old family Bible after it was discovered in Rarotonga.

The precious family heirloom features a handwritten family tree and was reunited with its owners thanks to power of social media. Source: 1 NEWS

The heirloom complete with a handwritten family tree has been in the Cook Islands for decades, only to be returned after a local lawyer tracked the family down on social media.

"I get quite emotional about it even, but that's because you're holding a family heirloom," Greg Van Slyke told 1 NEWS.

That heirloom, a Bible more than a hundred years old belonged to his grandmother Rubina May Faith.

Handwritten in the back is the family tree, complete with her own notes.

"It's got a really special significance as well as some of my cousins also interested in genealogy are just thrilled its coming back."

And it's all thanks to local Cook Island lawyer Paul Lynch.

"It was bought by a Cook Islands lawyer at a book auction in New Zealand maybe 40 years ago," he said.

"I often take declarations for people when they are swearing things they put their hand on the bible."

Mr Lynch told 1 NEWS he always wondered who it belonged to, so he took to a Facebook community page to track down the family.

"A Cook Islander in New Zealand accessed a genealogical page and within a few days and I had an email and I got to make contact with the grandson."

That grandson, Mr Van Slyke, flew to Rarotonga to collect it, and shed some light on how it left the family's hands in the first place.

"My uncle, after my grandmother and then her second husband had died, it came into his possession and I guess he was short of a buck or two, so he sold it."