The card is nicely gray, no color tint, made by a layer of paint. The base material is resembling dense cardboard, which might be ruined in water. No outdoor use unless you are sure it won't get wet.

The other side is neutral white which is also good.

There is no absolute color point mentioned, such as 6500 K. The card is not suitable for color matching, but rarely one buys 20€ stuff to do so anyway.