The term "hidden gem" is a metaphor used to describe something or someone that has not been widely recognized, but possesses exceptional qualities and potential. It implies that there is an element of discovery involved in finding this treasure - it's not immediately obvious, but once discovered, its value becomes apparent. The phrase can be applied to a variety of things such as a beautiful beach, a great restaurant, a talented artist or even a wonderful person who has yet to be recognized by the public at large. In essence, "hidden gem" refers to something that is underappreciated but truly remarkable once it's been uncovered.