Neherenia has lots of different forms. Here are some descriptions:
First Appearance: Shadowed Face, episode 148
Neherenia's face is conjured up by Zirconia to tell the Amazon Trio that they must capture Pegasus because it's the only way for her to return to real life. Not much other than her eyes and mouth are visible.
Present Appearance: (First seen) episode 149
The first time Neherenia appears in full view. Neherenia talks to Zirconia through the mirror in which she is trapped twice in this episode, seen both from Zirconia's point of view looking into the mirror and her point of view on the other side of it. She announces at the end of this episode that she is the true queen of the moon, Queen Neherenia.
Old Neherenia, episode 166
After Super Sailormoon defeats the Dead Moon Circus, Neherenia is taken up on a piece of rubble towards the New Moon, and Super Sailormoon follows. Neherenia has grown old and wrinkly without the power of dreams to keep her alive. She looks sort of like Zirconia, with white hair. Soon after, she reenters the mirror and returns to her normal appearance.
Teenaged Neherenia, episode 166
In a flashback, Neherenia is shown as a teenager, queen of the New Moon. She is very beautiful, younger than she is in the present and with shorter, prettier hair. She looks in the mirror and says that her dream is to be beautiful. She asks the mirror what the future of this dream will be, and the mirror shows an image of her as a very old and ugly woman (see above). Not wanting to lose her beauty, Neherenia becomes evil.
Chibi-Neherenia, episode 172
In another flashback, Neherenia is shown as little girl, princess of the New Moon. She's absolutlely adorable. In the first appearance, she is shown looking into a mirror. She reaches out and touches it, and her eyes glow golden. Later, after the Senshi heal her, Chibi-Neherenia wakes up in her throne room.