Elon Musk has offered a million doge bounty for anyone who can front up evidence that he or his family has ever owned an emerald mine.

The world’s richest man — who was born in South Africa — has been dogged by rumors that he’s a nepo baby.

In fact, he was born into an upper-middle-class family in Pretoria.

His mother Maye worked as a model and dietitian and his father Errol worked many jobs including as an engineer and property developer.

A number of news reports, such as one in the New Yorker, state Errol had an interest in an emerald mine.

But Musk disputes this.

Twitter account DogeDesigner wrote: “Elon Musk never owned an emerald mine. An open offer of 69.420 Doge to all the media outlets who are publishing false information. Send me proof of its existence & take your doge.”

And in response, Musk wrote: “I will pay a million Dogecoin for proof of this mine’s existence!”

That amounts to about $84,000.

That’s a small change for Musk, who has a net worth of about US$185 billion, according to the Forbes real-time billionaire list, mostly through his shares in Tesla and SpaceX.

Last year he wrote: “He [Errol] didn’t own an emerald mine & I worked my way through college, ending up ~$100k in student debt. I couldn’t even afford a 2nd PC at Zip2, so programmed it at night & the website only worked during the day. Where is this bs coming from?”

And Musk wrote in January: “The fake emerald mine thing is so annoying (sigh). Like where exactly is this thing anyway!?”

There is a report that claims he did once say his father owned a mine during an interview with Forbes in 2014.

“This is going to sound slightly crazy, but my father also had a share in an emerald mine in Zambia,” Musk was quoted as saying.

The article in question is no longer live on the Forbes website but is archived.

Fact-checking site Snopes reports that there is no evidence to support the emerald mine rumor.