It is the stone of truth and protection.
Obsidian is a stone anchored to reality. It gets rid of illusions and fantasies. It gives access to the light of knowledge and truth.
It helps know oneself, explore the dark areas of our memory and reveal the hidden pains and truths. It's the stone of introspection.
It stabilizes emotions and tempers overly harsh and brittle characters. It is the stone of absolute balance: it heals the soul, allows it to grow and prosper. This helps concentration during meditative research.
Last but not least, obsidian is considered to be the most powerful stone for protection. It acts as a protective shield against negative energies and harmful influences.