Packaging: jewellery box included stone size : 10 mm materials : aquamarine, fine silk cord, 925 sterling silver clasp length : 45 cm It has a shielding effect on your energy field and has even been used for physical protection during battle and at sea. The stone is said to help you sift through energy and information, create mental clarity, and soothe an overactive mind; it's even used to improve the intellect.