玉不琢，不成器

idiom: one must be trained/educated to succeed (lit. 'jade must be carved to become a vessel')
玉不琢，不成器

2 candidate readings from Wiktionary — genuine Chaozhou colloquial form not yet confirmed by a speaker. The two given candidates are not alternate pronunciations but the two comma-separated halves of one single reading for this proverb (split by the internal comma in the headword).