As one of the rulers of Homeworld, Blue Diamond has a massive size, with her towering height making her own Pearl appear tiny in comparison. However, her somewhat hunched posture, combined with her long, sweeping cloak, gives her a relatively smaller and more despondent silhouette than if she were standing straight.

Her complexion is azure, and she has long, straight, alice blue hair which curls inward at the ends. Two noticeable and symmetrical locks of her hair curl and point inwards towards her face just below her cheekbones. A unique feature of her hair are two lengths of that lead from each side of her head and physically connect on her chest just below her gem, giving it an almost shawl-like appearance. She has a long ovoid face, a full upper lip, and a straight nose. She also possesses large, sad, downward-slanting eyes with bold mascara on the lower lashes, giving the appearance of a weeping woman – most likely due to her depression over the supposed shattering of Pink Diamond. Her irises are cyan with black diamond-shaped pupils and she has thin arching eyebrows.

Her gemstone is located on her chest above her sternum, and she wears a long navy blue cloak that touches the ground. Underneath the upper part of her cloak, she wears a navy blue hood. Her height is similar to Yellow Diamond, only obscured by her hunched posture making her look shorter.