Looks like he used a clear adhesive when he should have used an off white methacrylate. Are theses seams exposed to sunlight? If he used polyester, they're going to get more yellow, not less, over time. I can't imagine by what magic these seams are supposed to lighten themselves. If called to repair this, I'd try to dig out as much adhesive as possible with a razor blade then tint some super glue to refill and scrape to flush. If done properly, the seams are stronger than the stone and separating them for a proper do-over could be catastrophic.

Wow. I will back you, ccsv - yes. Sometimes there are so many things that go wrong you have to triage what to deal with first and things like seams fall through the cracks. I believe you're right, whenever a person selling a product has specialized knowledge of their field (like your seam issue) the burden falls on them to explain it. You cannot know what you don't know since you haven't gone through it before - but they have. Many many times. So, don't feel bad. I do feel your pain and frustration though. That said, the kitchen looks great and I doubt it's worth risking the cabinets or the backsplash, etc.

@Alohairene if you have to leave your range on the long wall due to ventilation concerns, you might consider something like this (if you don't mind having a sink on your island). This wouldn't be my first choice but obviously ventilation requirements will drive some of your decisions. As for your question about the microwave drawer, I would just make sure it is near the refrigerator, since I primarily use my micro for reheating leftovers. If you use yours differently, think about what might be most convenient for your family. I personally prefer my microwave higher up (an under cabinet mount), but DH and I are tall and don't have to worry about children using it.

Thank you, Joseph and chispa. I really think something happened to the second stone that I purchased and that’s why they needed 3 more days before installing. (To get another slab brought in) Agree that if the dark colors would have been matched up, it would have been okay. However, what is so upsetting is that they aren’t communicating with us at all. We are towards the end of a major whole house remodel and need the countertops installed before sink and gas stove can be set. This is holding up our move in. How do I get them to remove and replace?