green, kingfisher
翠 centers on a vivid blue-green color, like the feathers of a kingfisher. The bird meaning is a specific application of that same striking color.
翠 combines 羽 (feathers) with 卒, which likely contributes the sound. The character originally referred to the kingfisher's blue-green plumage.
Feathers 羽 on top of a soldier 卒: imagine a soldier wearing a helmet adorned with brilliant kingfisher feathers, the vivid green standing out against the armor.
For スイ, picture a kingfisher diving into a Swiss lake: Swiss -> スイ, and the bird's green feathers flash in the water.
kingfisher
jade (stone)
kingfisher (esp. the common kingfisher, Alcedo atthis)
emerald
crested kingfisher (Megaceryle lugubris)
Midoriya
the sense of being engulfed in a green, mountainous atmosphere
approx. 80% of the way up a mountainside
Suimeiso (hotel and restaurant chain - suimeiso.co.jp)
verdant pine; green pine
green (esp. of trees, rocks, etc.)
green (of lush vegetation); verdure
dioptase
green eyebrow pencil; green-shaded eyebrows
jade green
blue-green
ruddy kingfisher (Halcyon coromanda)