Princess Crystal

Princess Crystal is a Fanfiction pony whose cutie mark is a crystal, very much like the jewelry, accessories and clothing she is wearing. Princess Crystal has a sleek, white body with the same body design as Princess Luna. She has a almost transparent pink mane with a similar hairstyle to Princess Celestia and Princess Luna, and her mane also flows. She is able to produce crystals, and has a evil sister named Princess Stoneleg, who is able only to produce stone, and was jealous of Princess Crystal's ability, resulting in her wanting to take revenge on whoever gave her this ability, thus turning her friends and family to stone. Princess Crystal stopped her by giving her to Stonehenge, an unicorn who was said to be able to make jealousy and sadness disappear from the mind.

Depiction in the series
Princess Crystal is a Alicorn princess who lives in a cave of crystals, residing in the Everfree Forest. When Twilight and her friends discovered her, she was in a bad state and eager to come with them to Canterlot, where she was fed and given shelter, however, Princess Stoneleg, her evil sister, broke into Canterlot and captured the princess, along with a few unlucky royal guards who tried to stop her, but instead ended up being captured too.