Nix

Nix is a purple colored ferret with a black-tipped tail and orange-colored Jewel Eyes. He seems a bit taller and thinner than the other Jewelpets due to his long body. He wears a light blue scarf pinned with an orange jewel.

In Jewelpet, he is one of the Jewel Eight and is brainwashed by Dian into doing evil; with his powers reversed, he makes people get into petty arguments. Rinko and the others reclaim him through the Jewel Games.

In Jewelpet Kira Deco, he is one of the ninjas (with Yuku and Chite) who wants to be noticed by others.

He is a background character in the other seasons.

(Source: Jewelpet Wikia)