The chiseled stone variant is called "Chiseled Stone Bricks" while it's blackstone counterpart is called "Chiseled Polished Blackstone" (without the "bricks").
It makes sense in Chiseled Nether Bricks because there is no non-brick variant, and there is a brick texture behind the skull.
Chiseled Sandstone and Chiseled Red Sandstone don't have a "bricks" on the end, and Chiseled Quartz Block has a "Block" on the end.
Since blackstone is supposed to be a Nether cobblestone, the names should match up.
Please remove the "bricks", "block" for consistency's sake (apart from the Nether Bricks because, as I said before, there is no non brick Nether Bricks).