The shelf is attached to solid blocking in the wall using a hidden steel angles.

Thanks, I appreciate your response, but can you please give me a little more information, i.e., what is the steel angle hidden by, and how is it attached to the solid blocking? I'm a homeowner renovating my kitchen and new to the terminology. Is a steel angle the same as a bracket? Are holes drilled in the tile?

These are pieces of steel welded together to make a bracket and are installed BEFORE the drywall goes on. Your tile, drywall, etc would all go around these steel angles.

Thank you! So does the angle itself form the shelf? In other words, nothing is then attached to it?