Can be kept in office or bedroom. Can also be used while meditation.
Angels can be kept around in office or bedroom to attract positive energy. You can also carry them in purse or pocket.
Black Onyx angel is known to keep away the negative energy and harmful energies which deplete our aura. It can be kept in the West direction or in any corner where you sense heavy energies.
You can also use it for manifestation. (Read the crystal manifestation blog).
If you are looking to gift some protection vibes to your friend or partner, then this can be combined with an amethyst or a rose quartz chakra tree or even a black onyx bracelet to make the perfect combo.