Black and Blue is a deep teal shimmer with Caribbean Sea-blue leanings.
The color is lovely (I never met a teal I couldn’t live with), but the formula is kinda watery. With two coats, I still had sheer spots.
You can see some brush stroke shenanigans going on above.
I really, really wanted this to be a winner, but considering that there are other dark teals out there that perform better, I would say this is not a must-have. Sephora by OPI Teal We Meet Again is a similar shade that has a better formula.