The mesh backing looks like a pale blue grout on my screen. I think it looks good.

If your nervous by such a large project. I’d sample a few grout colors on a spare sheet of tiles.

I am doing a very similar tile and we’re doing a glitter grout. See if they have something like this.

KR it looks beautiful! They are very similar but I’m looking to darken the tile a bit that’s why I think a grey grout will darken it

What color is the plaster? Coping? Patio?

A color that ties in all will work.

Get more of the same tile samples, glue them to a rigid piece of cardboard and apply all of the grouts your deciding on.

Let them dry and them take the outside with the other materials (plaster, coping, patio) and see how they look together.

In the natural light you'll get a better idea of the finished product.

I agree with another poster, you should have some grout samples added to a few sheets so you can see what it will look like. We have a dark blue (cobalt) tile and when they initially did the grout it was white and all you saw was white lines. we changed it to Platinum grey which is really dark, but it helps the blues pop!