I was thinking something more along the lines of the blackstone bricks being as black as coal, but having gray lines in between them where the cement would be. This would make them distinguishable enough from other blocks and it would prevent players from getting them confused with other black blocks at least the majority of the time.
To what BlackMonarch said I would say I'd just leave blackstone cobble alone, it is the bricks that are the biggest issue because having a dark gray colour they're too similar to Deepslate bricks in my honest opinion. And this defeats the entire point of adding deepslate bricks.
That works well enough for bricks. I'm not sure how useful it would be for black cobble or black smooth.
416 stone
296 stone slab (150 blocks)
149 stone stairs (228 blocks)
794 total stone
1082 blackstone
174 blackstone slab (87 blocks)
52 blackstone stairs (78 blocks)
1247 total blackstone
(not counting drawbridges and portcullises)
Good enough for me
To what BlackMonarch said I would say I'd just leave blackstone cobble alone, it is the bricks that are the biggest issue because having a dark gray colour they're too similar to Deepslate bricks in my honest opinion. And this defeats the entire point of adding deepslate bricks.