难能可贵
[词典] estimable; praiseworthy for one's excellent conduct; deserving praise for one's excellent performance or behaviour; rare and commendable;
[例句]一个6岁的男孩有这样惊人的造诣，真是难能可贵！
A six-year-old child with such an amazing attainment! It is indeed something rare and deserving praise.