The blue is much nicer than the green. It has such wonderful depth. If the countertop will be white, I think the black cabinet and blue tile will ground the room nicely without being too heavy. If the countertop is dark though, it will be too much.

Goodness, why so dark for a girl's bathroom! They are young and female!

I'm thinking you might have a bit too much going on there. The granite grabs attention. The floor will grab attention (due to penny tile pattern) and the cabinet finish isn't plain either. Where can the eye rest? All the components are beautiful, but all of them are divas. You need one diva and a bunch of supporting actors.

umm, what's age and gender got to do with bathroom colour?

Can you show a picture of the cabinets? The only black in the picture looks like a suitcase???

Forget about tiny specks of blue or green in the counters. They aren't going to be visible from any distance. If the tiles look good with the main colors of the counters then it'll work but if you're thinking it'll tie in with minuscule color flecks then re-think it.

Don't understand the addition of green tiles if the blue is too much? Blue and black not working so let's add green.

So is everything bought except the main floor tile?

In a children's bathroom, the fixtures and tiles should be neutral, but paint or wallpaper, towels, mirrors, accessories, should be age appropriate. Kids bathrooms should not have a dark feel, as childhood and adolescence is a time of fun, of hope for the future. Here's a Houzz search of girls bathrooms

http://www.houzz.com.au/photos/query/Girls-bathrooms/nqrwns

@Tribble, I disagree about the dark thing. If you do the same search but substitute "boy" for "girl" you get plenty of dark colours... and a complete lack of pink.

So when you walk into this bathroom, what will you see? Can you see the whole room at once? If so, reducing the number of finishes and colours would help. So, floor all one tile type and colour from door into shower; walls all one colour (e.g. tile and wallpaper both white); if your floor is going to be a diva, your counter should be subdued (e.g. a quartz version of Carrera marble).

Can't see dark on here, a predominance of light and bright

http://www.houzz.com.au/photos/query/Children%27s-bathrooms/nqrwns

Can you add a picture of the whole room? I love the blue penny tile. I plan to use penny tile somewhere, someday. I'm not sure about the blue penny tile with the black vanity or the vanity top.

I would do white penny tile...timeless and classic.....use blue towels and accessories to give that bright pop of color..or paint the walls a beautiful Tiffany box blue! Very Breafast at Tiffanys!!! Depending on your age you may not even know what I am taking about :)

HIWE, I like your first two pics.

The blue tile is beautiful. If you are just using it on the floors, it should be okay with the cabinets and countertop. Paint the walls white or white with the slightest tint of blue/green. However, I think it would look better if you change the black cabinets, which are very heavy and masculine, to a white cabinet. Or change the granite to a white quartz. Whatever you decide, only use one tile for the floors in both areas.