I'd build it up with 1/8" ply, glued and nailed with drywall roofing flathead nails. (scrap panelling, or ??
OR, might even check out 1/4" sheetrock, just to see what it'd look like raised?
Not sure how thick your border/edges are.

This is the molding. The thickest part that is going to the inside is 3/4" and the thin end 1/8" is going against tile.

Option 1. It's done all the time that way, and is actually a common solution to your problem.

When you're installing them, you can add 1/4" - 3/8" easily with the mortar. It's called "backbuttering" - put mortar on both wall and tile for the thinner tiles, and they'll even out.

Bumping to hopefully get some more opinions- need to decide by Monday!

Tile guy did tell me it would give a framed picture like effect if I went with option 1.

Haven't seen such a depth difference in person to be able to get a good idea though. Of course, he also said he can EASILY build up the back to make it level if I wanted!

Just double checked and the tiles are actually 3/8" so a bit MORE of a difference than I thought!

Can you get a thicker backerboard for that area? We almost had to do that since we used a different material behind our cooktop than the rest of the kitchen, but our moldings disguised it.

How thick are the glass tiles? That would be useful info for a design critique.
You have two problems the glass tile and the dif between the field tile- 3/8" and the 1/8" border side. Solving that brings the inside up to 1". Layout the segments and start changing the blocking to end up with what looks best in situ.
For example- 1/4" ply raises the border to field tile level and see what height the glass tile looks good at. Use something white or light because glass is often transparent and needs to be installed without notches.
Make sure you like the mix of mod glass and classical marble.

The glass is just over 1/16". It is not a "mod glass" tile, but an art piece that was custom cut- so not worried about mixing the materials. See pic below.

I hoped someone could post a pic of a similar scenario. The only thing close I could come up with is where the decorative section was recessed into the wall to create a small usable ledge for s/p etc. Maybe by going with option 1 it would look intentional, as if it were recessed. I especially like that look where there is a long counter run.

Here is a section if the design. The glass IRL is turquoise and not shiny-this is the protective overlay.

Your tile is beautiful. Hardi backerboard might be useful in this case to build it up. Wish I had a picture for you. Maybe you could do some mock ups to see how you feel about it being recessed or if you think it would be better to built it out to meet the other tile. Good luck!

We had the same dilemma. Our field tile in our BS are thicker than the bronze accent tiles we selected. We used Hardie backer board. It was easy to cut to fill the small spaces behind the tile and it adhered well to the wall and the tiles. I had also done some searches on line and found a discussion board that recommended using Ditra as backing for the thinner tiles. It comes in a roll and is supposed to be easy to use but it is a little more expensive and , according to the poster, had to be purchased in large quantities.

CML, that art glass is sooooo coastal modern!! It'll be fab in your kitchen.

Would it be a big style or tile faux pas to allow the different thicknesses to stand proud (or, um, un-proud since the art glass is thinner)? I understand if that is *not* the look that CML wants, but wouldn't the difference allow emphasis to focus on the art glass, as in the "framed picture" effect that the tile guy said? Wouldn't that be a good thing??

I hope this isn't perceived as a hijack, I sure don't intend it to be.

cheers

Stand out proud, I like that!

But I just got the craziest idea... Say I install it against the current drywall as is for a recessed look. Fast forward say-a couple years and I find another beautiful "art glass" mosaic. I could have 'that' piece made to fit over the current one and interchange them!! An interchangeable backsplash!!

The completed look is important to me because this is the view you see as you enter the house: ( apologies to those who've seen it a hundred times)

Closer:

I like your idea of swappable pieces. It's worth developing with some trial and error. Mounting the glass piece to a thin stable backer Opague plexi or galvanized sheet or a combination would allow a magnetic mount.

I could have my tile guy adhere magnets onto the wall prior to thinset- Genius Dan! He is creative and detail oriented so I don't believe he might consider me crazy- at least if the magnets are installed we can experiment with suitable backers after the fact. Now to find strong enough magnets...

I don't have an answer, but I can't wait to see that beautiful backsplash in place!

Now the thinness of the glass becomes a benefit. 1/16" plus 1/8" white plexi plus 1/32' steel sheet in several areas adhered with urethane or silicone could come to 1/4" and leave 1/2" for attached magnets and/or recess then 1/4" ply also running under the border to bring it up to field tile level.

Problem solved! Will post pics Monday!!