How blue is your collar; how long my heart has been turning on you.
诗经 · 子衿· our translation
A student's collar. Cao Cao quoted it to call for talent, and 青衿 became a name for scholars.
「青衿」是学子的衣领。曹操《短歌行》引它求贤，后世「青衿」就成了读书人的代称。名字用「青」，取的是这个青春与学问叠在一起的颜色。