At Orepuki, on the remote south coast of New Zealand’s South Island, a bed of riches colour the shoreline, bringing gem hunters from near and far

Jack Geerlings crouches down at the shoreline to sift through a bed of stones. He picks up a small rough rock and turns it over in his hands. “This one is too coarse,” he says and flicks it back to the pile. Geerlings is after something a little more interesting.

Slowly, he walks along the vast sweep of beach, his gaze rarely lifting from the ground. “The sunlight helps to reveal the stones,” he says, bending to pick up and inspect rocks one by one. A little further on, he turns over a small red-brown stone, the colour and texture of a chestnut. “This one could be jasper,” he says, with more enthusiasm.