Viewers of last night’s (Feb. 6) episode of Castle now have a unique opportunity to bid on a stunning piece of jewelry featured on the hit ABC series! The blue-diamond necklace (pictured above) at the center of the 1940s-inspired episode titled “The Blue Butterfly” – in which Castle (played by Nathan Fillion) is imagined as a hard-boiled gumshoe while he and Beckett (played by Stana Katic) investigate the murder of a modern-day treasure hunter at a legendary supper club – is now available in a special auction to benefit the charity organization World Vision. The auction for the necklace, designed by Castle costume designer Luke Reichle, closes February 14, so place your bid today!