black diamond
n.— «The competition has got tougher, but with this emerging market—the “black diamonds” as they’re called in the trade—people are buying homes, moving into homes, and upgrading. I think that market is in its infancy—it’s going to continue to grow.» —“Foschini earnings up 15%” by Lindsay Williams, Dennis Polak BusinessDay (Rosebank, South Africa) May 31, 2007. (source: Double-Tongued Dictionary)
Further reading
Twice a day the River Thames recedes, revealing a muddy shoreline. Hobbyists known as mudlarks stroll the surface searching for objects that have found their way into the river over the centuries, everything from ancient Roman jewelry to modern...