Princess D is from the D Kingdom (Diamond Kingdom) which is the world's largest producer of gemstones. She feels like no one cares about her only her diamonds.
She has short brown hair and wears a tiara. Princess D has very poor eyesight so she wears large glasses. When her glasses are off, she is shown to be very beautiful.
Nephrite uses a type of youma called a Soul Shadow to possess Princess D and steal the Silver Crystal. After she was freed from Nephrite's influence, she woke up confused, wondering where she was and where her glasses were, while the Sailor Senshi fled from the scene.
Princess D was seen revealing the special treasure, a statue of D's first queen, carved from a single 2000 carat diamond.