Jewelry designer Nina Runsdorf was at a trade show in the early 2000s when a “large brown rock” the size of a pebble caught ...

The most valuable black opal features bright red stone against a very black base. In the '80s and '90s, gem-quality brown diamonds were worth about $1,500 per carat, but now many sell for up to $ ...

Mike says, 'The different geological environments and formation processes are what causes imperfections in the stone - and these are what give diamonds their colour.' Many diamonds actually show very ...

The seller told her it was a rough brown diamond. Runsdorf ... Runsdorf bought it for $5,000, a steal for a stone of its size and quality. “It wasn’t considered precious,” she said.