Mystery Lady # 3

Because of my extraordinary resemblance to the Queen, I became involved in the hoax that brought her downfall. I was unaware of the deceitful nature of my adventure. I merely put on a beautiful gown and had my hair dressed, exactly as the Queen had the week before, and waited on the grounds of the palace to say five simple words to a grand gentleman. It was playacting. I was told the Queen would be watching and would be pleased if I did my part well. I lived in a dream that night… I had pleased the Queen! To my horror, a year later I was arrested for playing a part in an elaborate scheme to steal a great diamond necklace, which the jewelers thought they had sold to the Queen. I was sent to prison, but thankfully freed soon after, as I had no knowledge of the true nature of my crime.

Who am I?