I would say it's a chip that was epoxied back in. It most likely chipped when they fabricated it. The correct party is the fabricator.

Looks like part of the pattern.

Do you have a contractor overseeing the entire project or did you hire the fabricator on your own? If you are using a contractor, I would go to them, if not, then to the fabricator.

How disappointing! Make the fabricator fix this properly or replace the countertop. I hope he has not yet been paid in full.

It's a chip repair and poorly done at that. They couldn't even be bothered to tint the polyester. The yellowish cast of the adhesive is indicative of polyester, which is much less water resistant than the more expensive epoxy. This could be problematic in a high water area like a sink.

Please check the area to see if it was mechanically polished. Bounce some low level light off the repair. Does the finish on the repaired area match the rest? Can you feel it?

I'd check to see if there is a mechanical sink fastener in the chip area too.

The white quartzes are some of the most difficult to repair inconspicuously. At least he had the chip; I didn't:

I shoulda ripped the edge off, re-profiled, and polished, but they wanted to save money.

Drop the sink, remake the cutout on site with a nice positive sink reveal, and reinstall the sink.

Thanks everyone for the feedback! I spoke to the fabricator and lucky he was able to essentially buff off a 1/16" of the negative reveal on the back and it removed any evidence of the chip. Thankfully the chip was very shallow.

Hi Jennifer, I’m considering Rhino and I can’t find any installed photos. Could you please share your countertop photos?? I’d love to see what it looks like.