What is a gem coin?

Could you elaborate on the concept of a "gem coin" in the realm of cryptocurrency and finance? I'm curious to understand its definition, potential value, and how it differs from other digital currencies. Specifically, I'm interested in knowing if gem coins are backed by any tangible assets, their market performance, and if there are any unique features or benefits that make them stand out. Additionally, I'd like to know if gem coins are widely recognized and traded in the industry, and what kind of risks or opportunities they present for investors. Thank you for clarifying this concept.