Already graded Crystals and gems

you can npc them for like 1 meso i think

make like 1000mesos

You could also keep them and make yourself a hipster by saying

"I played maplestory when all they had was maker. You've probably never heard of it"

Or sell them to these so-called hipsters, oddly enough I've been selling some graded ores for more than I did when Maker was around, e.g. Basic versions of a variety of gems and crystals.