The black harmonizer is Shungite and the cray color is Soapstone that promotes positivity as it helps to soothe and balance your energy.
Hold the Shungite in your left hand and the soapstone in your right hand while meditating. Shungite is more yin, receptive energy, while soapstone is more yang, active energy.
Massage therapists, Reiki practitioners and Estheticians could give the harmonizers to hold to their clients while giving a session. It enhances the energy balansing for the client.