The fabricator will have resins they put in cracks. Your decision is if this is a product issue (along veining) seems like the stone isn't a great choice for this use.... Or if you are cool with him fixing it as he would any crack? I wonder over time if this stone will continue to show you it wasn't meant for this application?

Note, I have no expertise, but I would be concerned about it continuing to crack, both these current cracks worsening or new ones forming. They look rather severe.

Correct, do not count of chatgpt.

chatgpt is not who you ask about anything .THis looks like one solid slab was used for this so I ma not sure how badly these cracks will behave since they are in the center of the slab Real stone has fissures these might be those For me other than the pic of the corner seem to just be natural fissures relly hard to tell in close ups . I assum an undermount sink is the plan so maybe Joseph can help here if he is around. Once a slab is installed the movement in the stone is very minimal . I am curious why install before walls are finished but that is something else

I cannot tell completely from the photographs but it appears that it might be a void in the material. If that's the case, then it's more of a material issue instead of a fabricating issue. I always tell my clients that there are positives and negatives to each material selection, and the possibility of natural voids is one of the possible negatives of natural stone. Just the fact that it is now laying flat on your cabinets and not standing on end at the stone yard means that the stress on the material is different, which can cause this to appear a couple of days after install. If it is only on one surface, and not visible on the other side, then filling it with epoxy is a realistic remedy. As a designer, I've learned to trust my local fabricator's recommendations in these situations over the years. A reputable guy will tell you when there's a flaw in the material that isn't fixable.

I am curious why install before walls are finished but that is something else

Oh, I've been there before on an occupied remodel. It's a couple of weeks before a major holiday, and I'm willing to bet that time crunch was a factor. Looks like they cut the drywall for the old tile backsplash. Not a preferred situation, but when it's going to be concealed again with tile anyway, I've patched that drywall space after install has started.

I am always curious that is my nature. I doagree if the fabricator is one I have used before I usually trust thme and yes I have done drywall repair after counter never ideal

Fissures can sometimes crack under the vibration of transportation. A quick injection of resin can hold that together, and be stronger than the original stone's bond to itself. Looks like you chose a stone with lots of fissures, so double check any overhangs that you may have for proper support. Steel braces no further apart than 18"-24", and within 3" of the edge, for fissured stones.

Well these comments are making me feel better. Should the sink be better reinforced? Am I wrong in thinking that might be good to prevent any fissures from cracking?

The walls were not finished because the tiler plans to come in and put up backer board. Our timeline has not been smooth, everything was supposed to be done by tomorrow and what you see is what we have right now.

" Should the sink be better reinforced? "

How was the sink installed? Straps or the clip's that come with? If the clips, get rid of them, always straps. Unfortunately you have what appears to me to be natural stone fissures and veining. I would wait and see what the fabricator has to say but lots stone has naturally occurring veins that look like crack as and never get worse. Most are filled with a resin type epoxy with no issues.

The only thing holding up the sink is the epoxy and some wood pieces at each corner, no clips or straps. I don't like it.

I would not either. The best place for the clips is in the garbage. Use a HUSH or a Pesimoski Sink Strap. Joseph Corlett, LLC

Best practices in general, but you might be able to get it after the fact to help distribute the stresses on the stone.

The cracks look natural. Find out the specific adhesive he used for the sink please.

All looks like pre existing fissures to me. What is the adhesive, was a strap used, and HOW was it supported for a full 24 hours even with all that in place, As in a prop, showed in the sink cabinet, under the sink and snug as a bug.

What exactly IS the granite?

@ Joseph Corlett, LLC This is the adhesive

@ JAN MOYER This is Azure Mist granite. There are 1x2s under the sink in each corner, that is how it was held up. No strap and that is what we are going to add.