to cast pearls before swine; to give a valuable object or person to an unworthy recipient who cannot appreciate its worth

把这么名贵的古董送给那个不懂行的人，真是明珠暗投。

to not receive proper recognition for one's talents; a gifted person being wasted in an unsuitable or lowly position

他才华横溢却在偏僻的小镇做杂工，朋友们都感叹他明珠暗投。