This symbol is formed with the two initial for the word Christ: the X (chi) and P (rho). It has been a symbol for Christianism since the times of Constantin the Great, who was a believer of the prophecy "In Hoc Signo Vinces" (under this sign you will be victorious). This charm measures 0.97 inches in diameter, and it is offered as a single sided charm, with a solid 950 Sterling Silver back, or a a reversible charm, with the ICHTHUS symbol on the back (see inset). Also available as a solid 950 Sterling Silver key holder (Yes! the complete key holder is made out of Silver).