Dubbed the country's "first $1 million diamond" its whereabouts has been a mystery - until now, reports Kim Knight.

Diamonds are forever - but diamond mysteries are, eventually, solved.

For 15 years, the whereabouts of New Zealand's first $1 million diamond was a closely guarded secret.

This week, a South Island businessman finally confessed to its purchase, allowing the Weekend Herald to photograph the gem for the first time since its 2006 headline-making arrival.

The man, who wishes to remain anonymous, confirmed he bought the diamond as a gift for his wife - but she won't wear it, because the stone is so big.

"It just looks too big. You'd think it was a fake."

Dubbed the Star of New Zealand, the 52-carat raw stone was mined in South Africa and cut in Israel. It arrived in Auckland as a publicity stunt. When The Diamond Store closed for renovations, founder Win Charlebois set out to find something to guarantee good press on re-opening day. Sourced via New York's Beny Sofer Diamonds, the 19.5-carat rock created a media storm with round-the-clock security and an invitation-only champagne party reveal.

The Diamond Shop's Win Charlebois originally brought The Star of New Zealand to Auckland as a publicity stunt for his store renovations. (Photo / Paul Estcourt)

The mystery buyer - who collects precious jewels - said he had just returned from an overseas trip, when a friend alerted him to the sale.

"He said 'I thought you would have bought that diamond'. I didn't know what he was talking about . . . he sent me down the details and I thought 'yeah, that looks pretty good'. I actually bought it sight unseen, if you want to know the truth."

I did want to know the truth. Fifteen years ago, after news of the sale broke, an editor ordered me to find the Star of New Zealand. In the South Island, rumours swirled. I phoned many people - including the mystery businessman - but he denied all knowledge.

This week: "Yeah, sorry about that."

The Star of New Zealand, a 19.5-carat diamond, in a platinum ring setting. (Photo / Peter Meecham)

A phone call. A bank transfer. And, for the last decade and a half, the diamond has been "well-stored in a secure vault". Purchased in a temporary setting, it has since been fitted into a platinum ring - worn, for these photographs, by a worker at the hotel where the businessman agreed to meet the Weekend Herald. Afterwards, the photographer described the stone as "so big it could have come from a Princess Barbie dress-up box" and said the hotel worker guessed its top worth at $100,000.

"The bigger a diamond is, the more people think they're not proper," the owner said. "Up to about four-carat people will accept. After that, they don't even comment. They think it's a fake."

Why buy a $1 million gemstone?

"I just like it. It's something different. It's probably like buying a Rolls Royce or something like that."

He said the last time the Star of New Zealand was worn publicly was about six months after it was purchased.

"So I'm just storing it, and one day I suppose, when I kick the bucket, the kids will sell the thing".

Sera Cruickshank, director at The Diamond Store (since moved to Jervois Rd), said while diamonds generally dropped in value after sale, one this size would probably have increased in worth.

"People are looking for investment diamonds ... a 20-carat diamond is pretty much unseen in New Zealand."

She said it was difficult to know whether it would still be the country's largest, but agreed "a 20 carat just wouldn't be worn".

"It's way too large. And it poses a pretty significant security risk - if anyone believes it's even real."

Cruickshank said more recently, customers had expressed a preference for "lab-grown" over earth-mined diamonds.

"They are completely indistinguishable . . . the world's best gemologists can't tell them apart without special machinery. I'm actually looking for a 10-carat lab-grown for a customer at the moment."

Cruickshank estimated they accounted for 98 per cent of The Diamond Shop's current sales, and while they were "physically and chemically the same" they were generally priced 60 per cent cheaper than earth-mined gems.