Sardonyx towers in size; she is so tall that her hands are actually taller than Steven. She has vermilion skin and pale peach/apricot-colored hair, styled into a tetrahedron with very rounded corners. Her torso and legs greatly resemble Garnet's but have less mass. As a fusion, she has four arms and inherits the same locations of her gemstones as her fused cooperators. She wears a black, tailcoat tuxedo-leotard with a tangerine bow tie and a small, black star on her chest. This tailcoat comes from Pearl's sash ribbon. The underside of the tail of her tailcoat is the same shade of tangerine as her bow tie. She wears two-toned, mauve-gray leggings under crimson tips surrounding the top part of her feet. On her first set of arms, she wears white gloves, exposing her hands except a white covering on her middle fingers like Garnet's. On her second set of arms, located on her abdomen, she wears white gloves that closely resemble Sapphire's gloves that extend to her elbows.