I like the lighter one, plus the darker one will show more splashes behind the sink.

You need contrast...I’d do darker. My backsplash is charcoal but also looks black in photos. But with my under cabinet lighting on it looks blue gray. I love it, it’s different. Here are my pictures with and without under cabinet lights on.

Can you show it underneath the cabinet and against the counter? Those are the coordinating elements to consider.

More pics to show against counter top as requested.

Have you checked the tiles under the lighting you'll have under the cabinets? That might help you decide. (Why do you have only 24 hours to decide?)

The darker tile seems to darken the countertop whereas the lighter one blends very well. Have you had a chance to look at both options throughout a day? How do they look from afar, walking into the kitchen?

ETA: Your kitchen looks great, Karen Rose!

I really don't care for the black. It shows reflections a lot more that the lighter tile, and I think it is too much contrast. The lighter tile really does blend very well. It's a safe choice, which may be why you are feeling like you should choose something bolder. But in this case, "safe" looks great (and I'm usually the one lobbying for bolder choices in backsplashes).

I love the lighter color! It's going to be beautiful!

If I don't have the tile by Monday morning, the kitchen won't be finished this year. Unfortunately the electrical has not been done so I dont really have the ability to compare with lights without lights etc. I agree the lighter tile blends well and is the safe choice but wonder if it's just too meh. The cabinates are all white so right now the only colour is coming from the side panels and counter tops. Thanks all for taking your time to send me your opinions. Sigh. Still havent decided though.

You'd like it finished this year? I can understand that. On the other hand, I hate the idea of "rushing" a decision. FWIW, I don't think the lighter colour is "meh". But I'd need see it in proper context (the whole room) to be sure of my impression. The dark tile is mighty reflective in pics, as cawaps noted. Will that bother you? Any chance there's an issue with grout for the lighter colour tile? (It's glass, right?)

To me the black is too dark and the light is too light. Is there an option that is the same colour as the darkest striations in the counter? The light grey seems to be the same colour as the lightest striations. I often like a darker option for backsplash, but that black just seems to stark and not to relate to anything else in the room. Also, the lightest tile seems like a cold grey, whereas the darker colour in the counter seems to have some warmth to it (but could just be my monitor).

Yeah I like the lighter one with your counters as well. The extra photos you added really highlight it.

My first thought was splashes behind the sink. My second thought is keep it neutral like the rest of the house. You can add interest with what you put on your counters

Hi all, Just wanted to thank you all for your opinions. I actually did what Tartenmeup suggested - on Saturday I placed the tiles around the kitchen and keep looking at them from different perspectives, across the whole of the remaining day and into the night. I ended up going with the dark. They have started with the tiling and I must say it has elevated the kitchen. It has a nice warm hematite glow to it. Both tiles are glass, so although the pictures didn't show it as such, the lighter one was just as reflective - and no it doesn't bother me. If I was tiling all the way to the ceiling I would have gone lighter, but I'm just having a band along the one side to the other. @Karen Rose, your kitchen is stunning and inspirational! I will also be having lighting under the cabinets and I hope mine look as good as that! Is the lighting cool white or warm white?

Many thanks again to all who chimed in. I did appreciate all the responses.