瑜不掩瑕 Merits do not hide defects
Explanation
瑜指优点，瑕指缺点。指优点不能掩盖缺点，有时缺点反而更突出。
Yú refers to advantages, and Xiá refers to disadvantages. It means that advantages cannot cover up disadvantages, and sometimes disadvantages are even more prominent.
Origin Story
话说唐朝有个大才子叫李白，他诗歌才华横溢，名动天下，堪称一代诗仙。然而，他也有许多缺点：性格傲岸，狂放不羁，饮酒过度，甚至常有醉酒误事的情况。尽管他的诗歌成就举世无双，但这些缺点也常常为人诟病。后人评价他时，常常说到‘瑜不掩瑕’，既肯定了他的才华，也指出了他的不足。这就好比一块美玉，虽然光彩夺目，却也难免有瑕疵，这就是‘瑜不掩瑕’的真实写照。李白的诗歌，是那块闪耀光芒的美玉，而他个性的缺陷，则是美玉上的微小瑕疵。人们欣赏他的才华，同时也看到了他的不足。
It is said that there was a great literati named Li Bai in the Tang Dynasty, whose poetic talent was extraordinary and who was known throughout the land, he can be called the poet god. However, he also had many shortcomings: his character was arrogant and unrestrained, he drank too much alcohol, and even often made mistakes when drunk. Although his poetic achievements are unparalleled, these shortcomings were often criticized. When posterity evaluates him, they often mention 'Yú bù yǎn Xiá', both his talents and his shortcomings. This is like a beautiful jade stone, which, although dazzlingly shiny, can still have defects, this is an accurate portrayal of 'Yú bù yǎn Xiá'. Li Bai's poems are this shining jade stone, and the shortcomings of his character are the small defects of this beautiful stone. People admire his talent, but also see his shortcomings.
Usage
用来形容一个人既有优点也有缺点，优点掩盖不了缺点。
Used to describe a person who has both advantages and disadvantages, where the advantages cannot cover up the disadvantages.
Examples
-
他虽然有许多缺点，但优点也很多，可谓瑜不掩瑕。
tā suīrán yǒu xǔduō quēdiǎn, dàn yōudiǎn yě hěn duō, kě wèi yú bù yǎn xiá
Although he has many shortcomings, he also has many advantages, it can be said that the advantages do not conceal the shortcomings.
-
这篇文章构思精巧，但细节处理上仍有瑕疵，瑜不掩瑕。
zhè piān wénzhāng gòusī jīngqiǎo, dàn xìjié chǔlǐ shàng réng yǒu xiácī, yú bù yǎn xiá
This article is ingeniously conceived, but there are still flaws in the details, the merits do not conceal the defects..