Marlborough jeweller Corey Broughton is one of five people in the world to work with New Zealand's only precious gem.
He never imagined when he became a jeweller 22 years ago that he would be lucky enough to work with a stone as rare as ruby rock.
Working with the stone was similar to working with opal, but slightly more temperamental and much harder. "No two stones are ever the same, almost like a fingerprint," Mr Broughton said.
Ruby rock was very versatile and could be set in a variety of metals.
He preferred setting the redder stones in yellow gold and the green or blue stones in white gold or silver.
The potential of ruby rock was first recognised by Dutch-born master gemcutter Gerry Commandeur in Hokitika, when he began marketing the stone in 1998.
Mr Commandeur said all the ruby rock available was believed to have come from a single boulder weighing about 18 kilograms that was discovered during goldmining at Back Creek, Rimu, just south of Hokitika, in 1891.
"The place the ruby boulder originally came from has still not been discovered, but is believed to be at least 30 kilometres below the [Southern] Alps," he said.
Seaside Gems, in Picton, is the only jewellery store in the country to sell the gem.
Owner Alex Leitch said ruby rocks were desired for their beauty as well as their rarity.
"Ruby rock or goodletite is only found in Hokitika and nowhere else in the world," he said.
The one-of-a-kind pieces sold by Seaside Gems are created by Marlborough jewellers Paul Shepherd, Doug Owen and Hokitika jeweller Karen Shermun as well as by Mr Broughton, and priced from $300.
- The Marlborough Express