We have done two projects with Granstone over the past couple of years.
The first was in a townhouse, a difficult Quartz install with a large L, a large island, and an extended piece with a U cut out of the middle. We also had them do two bathrooms. The L was supposed to be seamless, but when they went to install it they realized that someone made a mistake and it was brought in two pieces. Granstone remedied their mistake and had that section re-made, and while the mistake was annoying, their customer service and remedy without any pushback was great.
When we moved into our new home last November, we had the builder not install the Granite and chose to have Granstone install Quartz after the fact. This is a huge kitchen, three massive slabs, plus three bathrooms. They did an excellent job again, at a very reasonable price for the amount of Quartz we had installed. A few little scuffs to the wall and a cracked piece of casing which we were happy to fix.
They made a small mistake which we noticed on the sink a couple weeks later, one of the bathroom sinks was the wrong color (close, but not quite right). Granstone came back and happily remedied the problem, even sending a plumber to re-hook up the drain lines afterwards.
We'll likely look to be doing our laundry room next, and it'll just be a small piece of Quartz, but we'll be working with them again.
All of the installers, Paige, Hayley, and company, wonderful to work with. Highly recommended.