I would not accept that, personally. How did they template?

Wood strips and hot glue.

No way would I accept that. Have him remove the counter and fabricate new. You can plainly see it is not in square. There is variation and there is you need glasses and maybe buy a level. Unacceptable.

Do not let the the installer back in your house and do not pay them one dime.

Call Lowe's and tell them to get someone out there - RIGHT NOW - that knows what they're doing.

Variation to this extent is definitely not expected if this top was properly measured. I would not accept this.

A 1/4" variation is pushing the boundaries of acceptability; you are well beyond that.

David Smith I would be getting them back to replace it now, as the back would have been cut and there is no way to move the stone forward without transferring the gap on the front to the back edge.

If you've got a splash thick enough to cover the gap, transferring a gap from the front to the back isn't a problem.

Lowes contractors are hit and miss. Call the manager of the department and have them come out to look at the work. Explain that it is unacceptable. and needs to be redone correctly. A few years ago we had similar problem with carpet wood floor installers from our local Lowes. After the manager saw the quality of installation they were removed from our project and we were supplied with a new contractor that did a wonderful job. Not sure I would ever use one of their contractors again even though the second one did a professional job. I think Lowes has a satisfaction guarantee. Good luck.

David Smith Good as they should.