Black agate transforms negativity into positivity. Agate enhances mental function, improves concentration, enhances perception, and analytical abilities. It is a soothing and calming gemstone that heals inner anger, anxiety, and helps in the strengthening of relationships. Agate instills security and safety in its wearer. Worn with onyx absorbs and transforms negative energy, and helps to prevent the drain of personal energy. … Black Onyx aids the development of emotional and physical strength and stamina, especially when support is needed during times of stress, confusion, or grief. Vintage and antique pieces containing onyx are usually quite valuable, as are some fine mixed gemstone pieces. The value increases dramatically when the stones are showcased in precious metal settings. Made in rope size with our logo swan hanging inside, it will make a wonderful gift.