|Lives:||The Diamond Kingdom|
|Occupation:||Crown Princess of the Diamond Kingdom|
|First Anime Appearance:||Romance Under the Moon! Usagi's First Kiss|
|First Manga Appearance:||Act 4 - Masquerade|
|First PGSM Appearance:||Replaced by a random rich girl|
|Princess Dia wearing her glasses|
Princess Dia was the shy spectacle wearing princess of the Diamond Kingdom, she owns a crystal that Luna thought might be the Silver Crystal and that she may have been the Moon Princess. It turned out that her crystal was a statue of herself, and that she was not the Moon Princess, she is one of the few minor characters that appears in both the anime and the manga.
- While Princess Dia herself doesn't appear in PGSM the storyline she is central too does, in it she has been replaced by a random rich girl who isn't a princess.
- Princess Dia looks somewhat like a female Gurio Umino when wearing her (very thick) spectacles, when she removes them she is actually very pretty but she has such terrible eyesight that this doesn't happen often. In the manga this led to the senshi very briefly wondering if Umino is also attractive without his glasses.