Diameter approx. 2.5 cm. Peter Stone Nebula Jewellery is Blessed by 9 Thai Monks and charged by them with crystals. Nebula looks just like highly polished silver, but is created using a tin based semi-precious metal alloyed with other non-toxic metals, such as zinc, for incredible strength and luster. Nebula is nickel and lead free as well as hypo-allergenic.