I'm glad you like it. Haha. Actually, aside from MC, all their names are their hair colours.
Geum is gold in Korean.
Ao is blue in Japanese.
And the Hong in Hong Yang's name uses the character for red.
Oops, went through my old notes and realized that last bit wasn't right. Although I had the initial intention of using 'Hong (红)' which means red, the characters I used for his name were actually 'Hong (弘) Yang (揚)'. Feel free to look up the meaning of his name =)