It looks like etching that happens with marble (when a glass is left on the counter - typically an entire circle isn't etched - instead there is a half of a circle like in the above photo).

Maybe it is an oil stain or something else was left on the counter for awhile which caused the issue - however, I didn't think that happened with quartz either.

I don't have quartz countertops - I know that they can be damaged - however, I thought it was difficult to do (except maybe due to heat).

How long have you had the countertops? If they've been installed recently, I my guess would be that the mark is related to the installer handles that are used to carry the quartz into the house to be installed (I'm sure that there is a technical term for them).

There are various ways to try to remove the mark (start with gentle and then move to options that are used to remove tougher marks). I've heard that many people use Simple Green to remove marks and then move onto Barkeeper's Friend (liquid) or acetone/rubbing alcohol.

Is this a new top or existing? If existing did it just appear or has it been there the entire time? Quartz is "typically" impervious to most stains & etching so I doubt it is that. Dani mentions the vacuum cups they use to move slabs but they would be a large full circle not just the perimeter and typically would be more than one if it were a large counter top.

@millworkman - that makes sense that the vacuum cups used to move slabs would leave a large full circle vs. the mark that is visible on OP's countertop.

OP - the questions that millworkman had asked above are important in order to try to narrow down what may have caused the issue shown in your photo. Will you take a photo with more lighting?

Are there any other similar marks on your countertops?

Do you have a soap dispenser sitting in that spot?

Did it get scorched when something hot was placed on it?

Did someone try to use a magic eraser to clean a spill/stain?

It appears someone my have put a hot pot on there.

It's heat or more likely a vacuum pod mark. Take a tape measure to your fabricator's shop please.