Here, I'll identify several of them, and -- more importantly -- explain the logic behind them.
My hope is that you’ll be able to extrapolate from this this logic to predict other Ethereal elements .
For Ethereality, put that shape -- the S curve -- in your head.
The S curve is crucial to Ethereality.
That’s because it's a line that's elongated, but that also curves. (Elongation is Ethereal.)
Braid detail is, of course, also Ethereal then. This includes braided metal in jewelry.
Spaced beads -- like those you see on a rosary -- are Ethereal, again because of the S curves created.
This is because, as lines, they're elongated, but they're also in motion, and movement is Ethereal.
(Diagonality suggests movement; the diagonality is a way of a line traveling from one point to another.)
For that same reason, flutter sleeves are Ethereal, winged shapes are Ethereal, feathers are Ethereal, and birds and winged motifs in prints are Ethereal -- as long as they're abstracted or stylized, not realistic. If they're realistic, they can be Ethereal plus a more literal style ID, such as Gamine, Ingenue or Classic.
Shimmer, shine and sparkle are Ethereal, in part because light itself is Ethereal, and in part because a shiny or sparkly finish reads as feminine.
A shimmery or gently sparkly finish is more Ethereal than a hard shininess because Ethereality is a gentle energy, not an aggressive energy.
Iridescence, which has a very gentle quality and suggests the sea, is particularly Ethereal.
If the prints are realistic, they're Ethereal plus another, more literal style ID, such as Gamine.
Godet skirts are Ethereal because they create sinuous lines and because they evoke mermaids, which are Ethereal. For the same reason, flares are Ethereal. (If they're flared jeans, that's Ethereal Natural.)
Speaking of which, waterfall effects, cascading effects and tiers are Ethereal, partly because they create the impression of gently diagonal downward movement, and partly because they evoke waterfalls, which we associate with infinity, beauty, and the ephemeral and intangible.
Cut-outs and mesh, if they're delicate but not sexy, can be Ethereal, because they're airy and light, because they suggest a world behind the current world, and because the very open weave generally creates S curves.
A very textured finish can also be Ethereal, if it's delicate, because it has the effect of being very visually busy -- i.e., highly detailed. Profusion of detail always reads as feminine, and Ethereality is highly feminine.
But realize that Kibbe groups all feminine identities -- Romantic, Ethereal, and Ingenue -- into one descriptor: Soft.
As a result, his recs for Soft types are sometimes more accurately assigned to Ethereal types and Ingenue types.
For example, Art Nouveau jewelry is really better for Ethereal Natural than it is for Romantic Natural. Romantic Natural needs more sexiness in her accessories; Art Nouveau design is generally rather chaste.)
Long hair is Ethereal because elongation is Ethereal. And of course S curves in long hair are particularly Ethereal.
Wispy and floaty hair is more Ethereal than smooth or slick hair, because it feels more insubstantial, and because it suggests a halo.
"Period" looks, if delicate, are Ethereal because they suggest agelessness, which is Ethereal.
(Distinguish "retro" and "vintage" from "period"; the first two terms imply decades of age, while the last one implies centuries. Vintage and retro aren't great for Ethereal, but can be good for Ingenue.)
This isn't an exhaustive list of Ethereal elements, but I hope it helps you think more clearly about the Ethereal style identity.
If you think you might be Ethereal, please check out my tools for identifying your own style identity!
And if you know you're Ethereal, please check out my Visual Style Guides and What Not To Wear guides.