Detailed Instructions: In this task, you're given a story (which contains five sentences only). Your task is to find all the characters which are available in the given story.
Q: Sentence1: Mary found an emerald stone in a cave while traveling. Sentence2: She had it examined by an expert to ascertain its value. Sentence3: As it was very valuable, she insured it. Sentence4: And she had it mounted as a necklace. Sentence5: When a thief stole it, she was rich, but missed her souvenir.
A:
Mary, Expert, Thief