There are well over 50 shades of grey, probably thousands of them which is why gray can be one of the hardest colours to match as there are so many versions of it.
There are two ways of making gray – by combining black and white (this is the easy way, and it’s easy to mix these greys together). Or by combining lots of colours til you get a grey, or adding a tiny bit of color to a grey, to take it away from being that cool gray made by black and white.
If you are warm look for greys that are: greenish or brownish.
If you are cool look for greys that are violetish, blueish, silver or charcoal