In the novel, "Number the Stars," Annemarie hid Ellen's necklace twice. The first time, when the soldiers came to her home, she grabbed it quickly from Ellen's neck and held it in her hand. When the soldiers left she saw that she had held it so tightly that it left a Star of David imprint on her skin.
Later in the book, after Ellen left, Annemarie hid the necklace once again, vowing to one day return it. She hid it in the trunk that held her late sister's belongings. It was wrapped in a skirt that Lise had worn. Near the end of the story, Annemarie was able to return the necklace to her friend.