I'd go further and consider just complimenting the person face-to-face and leave it at that. Help them understand their true value and that they should make sure they're not undervaluing themselves in terms of compensation or satisfaction.

That level of employee is either already recognized or they have idiots for managers. Praising them to an idiot boss probably just causes them more problems (jealousy for one or some point of praise gets twisted as them not following protocol -- maybe a report was late because they spent "too much" time with customers). If you go ahead, I agree with another commenter who said direct the feedback as high as possible to prevent jealousy or other backfire.

I'd agree with the manager approach if the person was so low level that it would be easy for their contribution to be missed.