CHAIN IS NOT INCLUDED. Available in Solid 14K Yellow or White Gold, or 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. Color Laser is a patent pending process, color is guaranteed to last forever. Color Medals can be worn in the pool, shower, etc. without affecting the image. We guarantee it. A guardian angel is a angel who protects and guides a particular person. The concept of tutelary angels and their hierarchy was extensively developed in Christianity in the 5th century by Pseudo-Dionysius the Areopagite. The theology of angels, and tutelary spirits, has undergone many refinements since the 400s, and contemporary orthodox belief in both the eastern and western churches is that guardian angels protect the body and present prayers to God, protecting whichever person God assigns them to. The Roman Catholic Church calendar of saints includes a memorial for guardian angels on October 2.