Nothing beats a childhood favorite! And lucky for us, Usagi's magical items are not only subtle in origin, but also make for great day-to-day jewelry.
This is Usagi Tsukino's season 1 (anime) transformation item: the brooch given to her by Luna. She received it in the very first episode and after transforming into Sailor Moon / Sailormoon, she wears it throught the entire "Dark Kingdom" arc.
The item can be worn as a pendant, or it can be attached to a ribbon and worn for cosplay purposes. As can be seen in the Shapeways 3D model view, the hook is hidden in the back.
Moon Prism Power, Make Up!