Most people have at some time or another heard about the hajj, the Islamic holy pilgrimage.  Every year millions of Muslims make their way to Mecca to worship before the most sacred object in the faith:  the Ka'aba, a giant stone structure, said to be built by Abraham, that houses the Black Stone given to humanity by God.

At the end of the Hajj Muslims celebrate the holiday of Eid ul-Adha, which commemorates Abraham's (and Ishmael's) willingness to obey God by sacrificing Abraham's son Isaac.  This holiday is marked in part by the slaughter of animals, echoing God's provision of a sheep as a substitute sacrifice.  

Gifts such as jewelry are also a common part of this celebration.  The above pendant depicting the Ka'aba aptly captures the connection between Eid and the Hajj.