I'm guessing this isn't commonly done....

I downloaded the photos of the 3 tiles and did a blend in Photoshop (yes, I am obsessing ;-) )

I realize this is a wildly inaccurate way to imagine it, but this is what it looks like in the drawing:
{{gwi:1496072}}

Too busy for the room?

Do any of your local tile stores carry these where you can see them in person? If not, it might be worth ordering samples of the three you're considering mixing, and looking at them side by side in your actual light.

I've never done this before, but if it were me that is what I would do! And, as you mentioned, over-order a bit more than normal.

Looks like a lovely bathroom!

Hi Marymt! Did you ever try this? We did something similar in my office, even though the tiles were from the same manufacturer and same tile series, there was some difference in the actual thickness and size of the tiles. It was labour intensive for our tile guy, but did end up looking nice. Definitely need to check the actual tiles against each other to check for size variation.
On another note, you may want to check the way you have extended the shower over the ledge. It is my understanding that any benches, ledges, etc., need to be INSIDE the pan. Perhaps the experts could comment.

It CAN be done, so long as the tiles are all from the same series. In fact, it's done quite often in the case of checkerboard floors. One thing you should be aware of, though-- there can be as much as a strong 1/16" difference in size from one color tile to the next (one of the reasons I hate doing checkerboard!), so be prepared to use a decent sized grout joint.

I took Stacey's advice and ordered samples of other colors in the series. But they each have their strong dominant color. They don't blend colors much within a single tile, and yet slate has that going on all over the place. So we may just go with real slate, for the walls at least. I'm considering one of the wood-look tiles for the floors. Caught in the vortex of indecision at the moment!

Thanks, Erica -- as it turns out, though, I think we're going with the tile shower floor after all, so the shower will be built with the bench.

And thanks Bill - of course, the classic checkerboard! I would not have guessed there'd be that much variation in thickness within a series. (Of course, real slate has that also, so either way there will be more labor...)

Am intrigued with quartz/quartzite, but that's another post....