Thank you javiwa! There is actually no overlap of the tile over the countertop in this area. The countertop starts past the edge of tile. Here's a photo after I removed the grout and what you see in the gap is silicon caulk with some grout debris still mixed in. I don't think this is stable or a long term fix. The caulk is basically suspended in air. The manager of the countertop division said the installer probably cut the slab back during install because he couldn't fit it under the tile there. I told him that the guy should've talked to me before doing such a thing because I was fully prepared to replace the backsplash if needed, reiterating that quality had been my number one concern. This is already a replacement of a botched job by my builder (which is why i wanted to see if they could possibly save the backsplash) in which they had chipped and scratched the original quartz and then filled it in with clear "hotshot" glue. It looked like a 2yr old had painted my countertop with clear fingernail polish.

There is a foam backer material used to caulk large gaps. Do an Internet search of "caulking large gaps". I have a bow in my wall which caused a similar situation. The caulk in that area has held up fine so far. Caulk does need to be redone now and then. I do have to fix an area where the caulk shrank behind my faucet where the fit of the countertop was fine. I live in an area of extreme changes in weather and that area is something I just have to keep up.

Saying quality is more important than saving the backsplash is subjective. It sounds like they tried to follow your directions to "try to save the backsplash". I think you'd have a better position if you'd said "if the counter won't fit under the backsplash stop the job and take out the backsplash". Were you there with the installer the entire time to help them make an on the spot decision to stop the install job and take out the tile? Sorry for playing devils advocate here but I can understand the installer's mindset (especially if he was getting paid by the job not by the hour).

Thank you both! I don't think foam backer is an option unfortunately because of the channel in the drywall behind from the previous installer.

I was there but working from home that day. I was originally scheduled for a Friday install and had taken the day off accordingly. They pushed me to Monday at the last minute due to some "setback in their shop" but I had meetings (conference calls) that day that I had to attend. So I was available just down the hall with my door open in case they needed to consult me on anything.

To me you ask a homeowner first if you're going to take any drastic measures like cutting their brand new stone short. I don't know what kind of issues were even possible to run into so I couldn't really give them a list of things to stop for. I didn't expect there to be a channel in the drywall for one. I guess i expect that they do this for a living, they are the licensed professionals, and i'm paying them for their expertise and services so they should advise me accordingly. They should know what the industry specifications are right? If the new countertop doesn't quite fit under the tile you ask the homeowner..."here's the situation...do you want us to cut the stone back or revert to replacing the backsplash?" Simple communication would've prevented this.

I really like the backsplash tile, hope it works out so you can keep it.