an uncut gem does not sparkle; success requires effort, not just talent
Proverb meaning that innate ability is not enough; one must polish one's skills through hard work. The literal image is of an unpolished gem that cannot shine.
As the saying goes, 'An uncut gem does not sparkle'; even if you have talent, you cannot succeed without effort.
A Japanese rendering of the Chinese maxim 玉不磨無光, “an unpolished gem has no light,” expressing the need to cultivate innate ability through effort.