|Species:||Humanoid; possibly psychic projection of Queen Nehellenia|
|Gender:||Female (anime); male (dub)|
|Lives:||The Dead Moon Circus tent|
|Occupation:||Ringmaster of the Dead Moon Circus|
|Associates:||Queen Nehellenia, Zircon, Amazon Trio, Amazoness Quartet|
|First Anime Appearance:||Meeting of Fate! The Night Where a Pegasus Flies|
|First Manga Appearance:||Act 39 Yume 1 Nisshoku Dream|
|First PGSM Appearance:||N/A|
|Actors:||Hisako Kyouda (anime), Robert Bockstael (dub), Barbara Goodson (Viz dub), Naomi Watanabe (Sailor Moon Eternal)|
Zirconia was the ringmaster of the Dead Moon Circus and commander of the Dead Moon forces prior to Queen Nehellenia's release from her mirror. She was always accompanied by the creature known as Zircon.
The Materials Collection states that Zirconia's body looked like an insect's, without flesh, and that she had been alive for tens of thousands of years.
Zirconia was possibly the physical manifestation of Queen Nehellenia's nightmare of growing old and ugly.
In the Sailor Moon SuperS Special Musical Show, there was a character called "Neo Zirconia" (ネオジルコニア), also played by Keiko Iseki.
- In episode 143 of the first English dub, the Amazoness Quartet gave Zirconia several nicknames, such as "Zerc," "Zercie," "Zirco," and "Zerc the Jerk."
- In the first English, Portuguese, French, Hungarian, Greek, Spanish, and Turkish dubs, Zirconia was changed to be male.