Natural black tourmaline stone pendant, adjustable size. - Material: Black tourmaline - Pendant shape: Natural stone shape - Size adjustment: With adjuster 3 x 1.6 Meaning and effects of black tourmaline | October birthstone Black tourmaline is the strongest protective stone with powerful effects of warding off evil spirits, protection against evil, stress reduction, and blocking electromagnetic waves. It absorbs and purifies negative energy, balances mind and body, and supports "grounding" to keep you grounded, making it ideal as a talisman for mental health and maintaining well-being. Thank you for looking.