A plague upon all your households. You are filth. Less than human.
The joy you feel now will soon pall, and be replaced all too quickly by the overwhelming loss of your own dignity. The curse now invoked, will never end while you retain these treasures, which belong to all of us.
You will die poor in spirit, you will never be recognised, you will always live in fear of those who hunt you. Simply give the pieces back. At least then you can say you did one good thing in your lives.
In the meantime: for all our sakes, at least care for these works of art. They are imbued with more humanity than you will ever possess.