Also known as: ダークジュエル
When Hoshina Utau character transforms with Hinamori Amu's Guardian Chara Dia (Shugo Chara!), she turns into Dark Jewel. Similarly to Dia, she has a Diamond (Shape) motif.
However, because Utau is not Dia's owner, the transformation drains a lot of her energy and does not last long.