when they were filming twilight there came up and created the cullen crest so the cullen could wear it as jewellery to show they are unity and a family! like rosalie would wear it as a necklace, alice a choker, carlsle and esme rings and edward, emmett +jasper a waistband. i think it a nice touch, like they came up with the tatoo for the werewolves to show their commintment for the pack to show their all "brothers" hope i helped!