Mr Selman said of the theft, "It's interesting to me that someone felt they like the work enough to steal it.
"I suppose it's flattering in a way, but at the same time I have to wonder how they could enjoy looking at it while knowing that it's been stolen from someone."
The gallery is not insured for the theft because it happened when they were open for business. "If they'd broken in and stolen it, it would be covered," Ms Sanderson said.
This is only the second time in ten years that a piece has been stolen from the gallery.
"It's not what you need. We're just a small business with only three staff here. A loss like that is quite a big deal for us."
The gallery is asking for anyone with any information about the piece to contact them directly. A reward is being offered for the return of the work.