the primary distinction, to start is: precious and semiprecious (when making something. properly making something, certain artificial anxieties fade. at my worst, my urge here would be to caveat, hur dur, per the first line of wikipedia lol--in some preemptive fashion, in case someone familiar with wikipedia's article sees this and thinks: lol nice one idiot you copied wikipedia.. or hmph.. how simple.. such elementary knowledge.. anyways. such doubting thoughts are barefaced in their stupidity, in the process of producing even a markup file. maybe in the act of actually producing rather than consuming there's a certain confidence overwriting the agencyless anxiety of scrolling an infinite feed of cynicism and insecurity, from all angles, such that if you tried to preemptively defend against all of it, the only course of action would be to kill yourself. ig that's half the appeal of neocities and etc. your space: not measured relative to anyone else's. emerald, ruby, sapphire , diamond: the precious and the semi-precious: the rest. also called hardstones (neat!) a gemologist identifies gemstones with fun, hard and fast, technical characteristics. most obviously:
chemical composition

diamonds are carbon

rubies AND sapphires are made of aluminum oxide: Al2O3

maybe the play is a website where its like a taxonomical tree of gems. in fact multiple, per the different ways of organizing them. by chem composition, and if certain elemental combinations don't work, explain why. or under what crazy circumstances it could happen.
crystal systems, habit
groups, species, varieties66