4 mm -- 16g/0.05 lb stretch bracelet.   Silver Sheen Obsidian is a soothing, protective stone for those of us who have issues with a possessive  parent or partner, or who need help keeping firm boundaries. 
Silver Sheen Obsidian is a marvelous stone for out-of-body journeying as it provides a strong connection between the physical and astral bodies, and assures a safe soul return.