As a fan of cool rocks and gems, and putting aside price and societal influences, diamonds are cool!

Especially compared to hard plastic “costume jewelry” (which I think you’re referring to), gems are hard, don’t scratch as easily as hard plastics, and have cool reflections.

Referring to mossanite and cubic zirconia, which are completely indistinguishable to a normal person, and can be had for dollars per carat.