This costume is referred to as "Triton" in the costume design. I named her "Diana the hunt goddess" is because she wears the attributtes of the Roman goddess Diana.

Originally Diana was the virgin goddess of fertility and hunt, but later she also became a moon goddess, supplanting Luna, and the crescending moon is a symbol for Diana in Western art. She was popular in England and France from the Renaissance and up; in England she was a paraphrase on Queen Elizabeth I, the virgin queen, and at Versailles she was incorporated into the Olympian iconography with which Louis XIV "Sun King" liked to surround himself.

Whether this is enough to classify the stage costume as a Diana costume... Well, the link is loose, but fitting. The costume carries many references to the sky, with stars and moons and skyblue colours. But as mentioned, the costume design names her a triton (I.E. a messenger of the sea), and it's not hard to spot the sea symbolism either.

Her costume consists of a corseted, tight-fitting turquoise bodice with gold decorations. The neck opening, as well as her tiara and mask-on-stick carries some sort of wing symbolism a la Hermes, which is fitting for her role as a messenger of Poseidon. There's also either stars or bells going down the front bodice. The skirt is made of various light fabrics in golden, turquoise and sometimes black nuances, decorated with a fringe hem and a golden rope with stars and tassels around the waist. There's also a twisted or braided drape around her waist. A glittering, light backdrape is fastened to her shoulders and wrists, giving a nice effect when she's dancing.

The legs are covered with bright red tights and high-heeled boots, very often the same as Christine wears for her "Star princess" dress. Sometimes she wears lower boots with wings in front. She also wears a turquoise wig with ringlets in a ponytail.

The red tights might seem out of context of the otherwise delicate turquoise and metallic nuances. But when zooming in on the design, once can see that the skirt originally was meant to be multicoloured, with turquoise, metallic, black AND red pattern. This forms a nice transaction from bodice to skirt to tights. Few stage costumes has picked up this, however. Closest thing I'v seen is the Australian ones, which use a transparent turquoise/golden fabric for the skirt, which allows the red tights to be seen through.

It was also interesting to see how much star symbolism the original West End costume had. There were beaded fringes with stars at the skirt hem, beaded strings with stars at the shoulder/drape, golden stars on the red tights, and a star in the tiara. Maybe it was to avoid this costume overlapping that of Christine, the "Star princess", that some of it was toned down. Newer versions usually have a star in the tiara, but only sometimes the crescent moon.