Ruby (ルビーRubii?)
Jewel: Ruby
Species: Japanese Hare
Gender: Female
Jewel Power: Courage
Attribute: Magical Red
Voiced by: Ayaka Saito

Ruby is Rinko and Akari's Jewelpet partner and the secondary heroine of all three series. She is a White Japanese Hare who symbolizes courage and wears a pink and red cherry blossom on her head. She also wears a necklace shaped like a pair of red cherries. Ruby is the only Jewelpet who has the "Acrylic Class" ranking due to her magic, which can cause bad luck and explosions when she casts it to someone but sometimes her magic has 1% chance of success. Due to her bad behavior, in-attendance and goofing off, she was punished by the Four Great Magicians of Jewel Land, turning her into a Jewel Charm and sent her to Earth to find all of her lost friends. Her Jewel Charm form fell into Rinko's drinking glass on that night and then being awakened by Rinko's Magic using the Jewel Pocketbook the next day. Her personality is a bit joyful, brash, happy and sometimes a BIG troublemaker, which makes her partner Rinko have a hard time handling her. Despite all of this, she and Rinko were appointed to find the other missing Jewelpets on Earth and handling every problem her partner encounters. It's revealed that Ruby is the ancestor of the savior of both the Human World and Jewel Land along with Rinko's Ancestor. She has a big crush on Tour the American shorthair cat and sometimes called "Romper Lady" by him. in Episode 51, She earned her "Superior Crystal Class" rank in magic after a trial given to her and summoned Opal the unicorn in the final battle against Dark Dian. But then she found out that it was temporary as she is now back as an Acrylic Class Jewelpet.

In Jewelpet Twinkle, Ruby is a new Student in the Magic Academy. Her first test to get in is to find a Human Partner on Earth which the feelings of her heart matches hers, which happens after she met Akari. After that, she got accepted in the academy along with Akari and lives with her in the human world. She also acts as Labra's older sister, sometimes knew what's best for her. In Jewelpet Sunshine, she is one of the students of Jewel Land's Sunshine Academy and also Kanon's Roommate, who sometimes, they can't get along together. But there are some situations that both her and Kanon need to work together. She has a huge crush on Mikage, in which the cause of her Rivalry with Kanon years ago. Her birthday is on July 29 and her name is based on the Gemstone Ruby.

Ruby can also use the Jewel Pocketbook to awaken Jewelpets from their jewel forms. She can also wield a miniaturized version of the Jewel Stick for her magic or with Garnet and Sapphy, to summon other Jewelpets from Jewel Land. She has also the ability to summon Opal. In Season 2, Ruby is one of the Jewelpets who can use the Jewel Pod while she and Labra can cast magic together with Akari during some situations in Jewel Land.