An art trader has sent a stark warning to thieves who stole a C.F. Goldie painting in Hamilton.
The work by the colonial-era portraitist went missing between December 27 and January 3, and police are appealing for information.
'Sleep 'tis a Gentle Thing' was taken along with other unique artworks and antiques.
The head of art at Webbs Auction House, Charles Ninow, said the best thing the thieves could do for themselves was to hand the painting in.
He said the work is so recognisable they'd soon find they won't be able to sell it.
"I would urge them to return the work and take it back to its rightful place, and give it back to the owners who care about the work, and have been its custodians for the last decade."
Ninow said the longer they held onto the painting the greater the risk somebody would eventually leak its whereabouts.
Goldie produced several versions of the painting.
The director of the International Art Centre, Richard Thomson, sold one for $454,000 in 2009.
After reviewing a police photo of the item, he has earlier said it looked like the same one and could be worth $1 million now.