Available in Sterling Silver Size Reference: 17mm is the size of a US dime 21mm is the size of a US nickel 24mm is the size of a US quarter The Sacred Heart of Jesus Keychain can be engraved with a personalized message on the reverse side Available in Sterling Silver . Medal in two sizes: 3/4 Inch x 3/4 Inch (Size of a Nickel) 1 Inch x 1 Inch (Size of a Quarter) Custom Sized Available Upon Request. The Sacred Heart is a religious devotion to Jesus physical heart as the representation of the divine love for humanity. This devotion is predominantly used in the Roman Catholic Church and also used in the Anglican Church, particularly among Anglo-Catholics. It also stresses the central Christian concept of loving and adoring Jesus. The origin of this devotion in its modern form is derived from a French Catholic nun Marguerite Marie Alacoque, who said she learned the devotion from Jesus in visions.