Samantha's Witchcraft Blows a Fuse - S8-E25
Other mistake: When the police pull up outside the Stephens' home, it is a set shot with fake background. The "road" doesn't match the outside of Stephens' neighborhood shown throughout the series with the Kravitz house across the street (and not a pine tree forest as shown here).
Answer: The original diamond and white gold heart necklace was given to Elizabeth Montgomery by her then real-life husband, William Asher, who also directed the show. She wore it in nearly every early episode. When the necklace was lost or stolen about mid-way through the series, Montgomery had two replicas made from rhinestones. She wore either one of those for the rest of the show's run.
raywest ★