I just staged a home with a small bathroom that needed a large mirror. I bought a 1/4" plate glass mirror (no bevel) and small square glass feature tiles from Home Depot. I first laid the mirror and tiles out on the floor exactly how I wanted it to be on the wall. Then, I had the mirror professionally cut down to the exact size needed to accommodate my tile border without having to cut any tiles. I nailed a 2 X 4 to the wall to mark where the bottom of the mirror would be, to support the mirror temporarily. Then, I glued the mirror to the wall with Mastik (with another person's help). I let it set overnight, bracing the top of the mirror in place with a make-shift 2 X 4 knee brace. The next day, I adhered the tiles in place, and when that was dry, grouted the tile.
There were lots of positive comments about it by potential homeowners and realtors.