This jewelry armoire had the 3 features I was looking for: size, lockability, and mirror exterior.
One reviewer mentioned that they wished the cabinet would mount to the wall from the inside. I actually had the same thought. So after mounting it inside my walk-in closet, I peeled down the top section of the ring storage a little and drilled through to the wall behind with a small bit. I then took it off the wall and drilled slightly larger pilot holes and tapped in spring loaded metal wall anchors with a hammer. I then remounted the armoire and, using my power drill, started the machine screws into the wall anchors. Half an inch from being flush to the rear of the cabinet interior, I tapped them in with a hammer and continued to tighten until the cabinet was really locked into the wall. I was able to pull the bottom away from the wall a little and installed a long strip of thick gel-type double sided sticky to add extra stability and security.
I feel fairly confident that it would be too much work to remove the armoire if someone thought to look inside my closet. Not that I have expensive stuff, but I feel better with the additional security.