The thing about safes* that does not make them viable solutions as to put items of extreme worth (unless it is in a bank) is the 'sore thumb' factor. They stick out like a, well, sore thumb. Any burglar with a touch of sense would run into the house with his accomplices and run off with the safe, as
it's the most obvious place a person would put his or her possessions.
This could easily be solved by removing the 'sore thumb' factor.
Stamp Safes would be designed for stamps or other small items of worth, and would be designed to be pretty small, small enough for a few stamps, or perhaps a few bigger items to be put in, then they can be put anywhere in the house, such as under the floorboards, in the walls, in another safe that's buried in the garden, etc.
The safe would be so small as that you might need a pair of tweezers and a magnifying glass to see the numbers and rotate the wheel thingummy. This might sound unreasonable or illogical, but Stamp Safes would be small enough to need mechanical tools to open, but too big for hand tools to open it without risking the destruction of the objects inside.
* I am talking about the kind of safe that can be lifted up and carted off, not the kind that is imbedded in walls.