The phrase "black marble" refers to when a person or entity receives no points or recognition for their achievements or efforts. It means they have failed or been unsuccessful. Full definition
Black and white bathroom with small white stacked tiles framed with black marble border tiles creating the illusion of framed wall panels. (decorpad.com)
Meanwhile, the fully equipped kitchen has black marble countertops and a center island. (luxuryretreats.com)
The new bathrooms are mostly gray and white marble, with a splash of black marble on the walls above the tubs. (petergreenberg.com)