This art's name is kûmbak/geumbak 금박 (金箔) "gold foil, gold foiling".
The art of goldsmithing was likely introduced in the Korean peninsula from Central Asia though the Manchurian corridor by Goguryeo
metmuseum.org/exhibitions/li…
metmuseum.org/exhibitions/li…
A good example of this trade is the Hwarot (활옷, 闊衣 ), a dress built on the model of Khotan Kingdom (于闐, 于窴, or 於闐)'s, allegedly introduced during the Goryeo Dynasty. Similar garments existed precariously for the queens, btw. 
An example of a royal attire during United Silla period (in this case: Queen Seondeok 선덕여왕 善德女王, c.a 595~610-647):
As in China, the art of smithing was highly valued. But unlike it's powerful neighbour, Korean kingdoms were on a territory filled with metal, therefore we can easily find metal reperts in almost every tumulus, regardless it was royal or aristocratic.
An interesting outcome of this is the now mainstream habit in Korea of using metal chopsticks and spoon.
Trivia: traditionally, nobility used it crafted in silver, both as status symbol and to avoid poisoning.
blog.snackfever.com/2017/02/korean…
Trivia: traditionally, nobility used it crafted in silver, both as status symbol and to avoid poisoning.
blog.snackfever.com/2017/02/korean…
@threadreaderapp please unroll, 感謝
