Can Nebelung cats be black?

In terms of breed standard, no, Nebelung cats cannot have a black coat. The breed is specifically known for its blue-gray coat. The breeding goal for Nebelungs was to create a long-haired version of the Russian Blue. Black fur is not a recognized color for this breed, and any deviation from the standard coat color would not be in line with the breed’s established characteristics. But of course, this is only really important for show standards, and deviations in coat color doesn’t diminish the character of a Nebelung cat in the slightest.