I suggest you immefiately discuss your concerns with your installer. The cut out around the window is a poor job and not acceptable, in my opinion.

You arent fixing that. Epoxy fill is about it. They will not do any better with a brittle, chippy, difficuly to cut, stone.

They need to do an insert style repair. You'll probably always be able to see it, but the home inspector for your buyers when you go to sell won't. Insist or use the balance you owe them to pay to have it done please.

Do you have an example of that?

This could have been made more inconspicuous with a bit more work.

Joseph Corlett: you do amazing transformations!!