Your first picture is easily fixed by making the radius larger, re-profiling and refinishing the corner.

The second is just a poor quality seam. That's never going to look good unless it's done over with a Seam Phantom or taken back to the shop and both edges dressed on a CNC machine.

The miters in the third picture stretch the limits of acceptability. Not a bad color match, but he should have made you a mock up that you approved in advance. He's sorrier than you are that he didn't, I'll bet.

You don't use white caulk with a white sink. You use a caulk that matches the stone, not the sink. You bring the stone to the sink, not the sink to the stone. Clear or Axiom Translucent White would have been a much better choice, but it's the poor detailing here causing the problem. The notch should have been eliminated.

A white sink properly caulked with clear silicone.

Your last picture looks like an impact mark. With such a consistent color/particulate stone, that's going to be very difficult to be made to appear inconspicuous. I'll bet you can feel it too.

Had I broken 3 mitered pieces in half, you would have never found them.

Sorry to say but the mitering work on this photos is of very poor craftsmanship and I am posting this for any future reference and advice to anyone interested on mitered projects.

Everybody should know that working with miters properly takes experience and the mitering "know how". From planning, templating, cutting, finishing and installing.

It is very important for every customer to make sure that his fabricator can do the job right.

Seeing beautiful samples of mainstream granite works cannot guarantee that your mitered project will be done properly cause mitering is "another chapter" and needs advanced craftsmanship.

When you are searching for a fabricator to do your miter work you have to see the miter projects of this fabricator including close up neccesarily.

There are good fabricators out there but you have to able to identify them through their work.

This is how a very good mitered quartzite project should look like :

Taj Mahal quartzite mitered polygon island

Cristallo Cube quartzite mitered island

Nice pics but you're not showing the miters or the seams.

This is a mitered edge on quartzite

That ^ better have a steel structure underneath or gravity is going to pull those waterfall miters apart when the center sags, I promise.

This job is not professional and unacceptable. Your fabricator is making up excuses for the poor workmanship. Hopefully you didn’t make the mistake by paying in full up front.

Yes, it's absolutely necessary a steel support underneath, and we did, since the leg and crossing the table.

Quartzite has a very large liquid absorption capacity, those darkened stains on the edges are caused by little hardener in the glue, some glues, if a little hardener is used, begin to release a sticky resin that is absorbed by the quartzite, modifying its color.