Jewel is a large humanoid demon with a diamond cased body, he has an insect like head with four eyes and mandibles, a large gem in his forehead.
His diamond body made him incredibly tough, he was very agile and attacked with a small blade capable of slicing a demon straight through. He was capable of teleporting through mirrors and had telekinesis allowing him to psychically hurl objects with his mind.
Jewel was a fastidious killer well known for his cruelty, so much so he was even in the good graces of Demon King Zennon. Jewel frequently referred to himself in the third person and was described as highly intelligent several times.
Jewel is first seen on a hunt, having been given an exact replica of Devilman to kill. He chases the body double down to a clearing before pulling out his blade and slicing the double in half. Afterwards he is congratulated by Zennon, who then gifts him the task of killing the real Devilman.
Jewel travels to the Makimura home and begins terrorising the residents before trashing Akira's room, calling him out. Akira has trouble sensing Jewel but traces him to a nearby forest where the two square off. Jewel throws attack after attack as Devilman is beaten down, unable to even scratch the shining devil. Finally Jewel pulled out his knife for the final blow, as he jumps Devilman spots a weak spot in his eyes and extends his antenna, stabbing Jewel in the eyes. Stalled from the pain, Devilman then electrocutes him with Devil Shock, ending the gemstone devil's terror.
- A scene with Jewel terrorising Kensaku Makimura inside of a mirror is strongly reminiscent of Ghelmer's attack in the original Devilman manga.