you could lay them out on the front of the border, if that's what you mean. But, because they are see-though, you'll have back comb your thinset flat so the ridges don't show through. and use white mortar. you'd also have to use some other type of tile or be prepared to cut these.

or, could you use them just on the top, and some other type of tile down the sides?

if you did something like these black tiles on the face, and the glass on top, it might work

another idea is to outline the door w/the tile

what is going on the ground ? cement? tile? stepping stones?

if you could do some black and white cement tiles w/your glass tiles, might look cool

I guess it's too late to integrate lights into the planters. But I bet you're doing the walkway next. Remember the lighted sidewalks from the..hmmm...1920s?

https://en.wikipedia.org/wiki/Pavement_light

Wow, what an interesting link! Thanks for sending. To integrate lights into the planters to set off the tiles would be fabulous but involve a whole new design and construction plan including electrical, etc. and I'm just too far along to do that. And as you can see from this "before'" picture, I don't really have a walkway. But thanks.

What a great find! It seems to me that any incorporation into the planters might run the risk of them being covered by plant material over time. I'd treat them as a sculptural element in the garden. You could have them re-leaded into a panel (see an original one below) and hang it in front of the window to the left of the door. That would give interest from inside and outside.

I think to do those tiles on a planter is doing them a disservice . I love the idea of framing them and placing them where the light shines through them. Luxfer tilesa re awesome and IMO need to have light showing through them , I also like the idea of them bing used as alighted part of a walkway but maybe more work that you want.