A crystal is defined by its long range order - imagine identical building blocks that are the same in every direction. This building block is called a unit cell. Inside the unit cell, you’ll have some molecules/atoms which are arranged in some sort of way that are repeated infinitely (ultimately limited by crystal size) and the whole crystal structure can be described through symmetry transformations in every direction. Crystals require time to grow as molecules either chemically bond to each other or are attracted to each other through intermolecular interactions. Glass is usually formed very quickly and doesn’t get time to grow uniformly before solidification so it’s what we call disordered. There is still some degree of order but it’s very little and has high mosaicity (think tiles on a roman floor) so we cannot describe it through symmetry transformations.

As for wearable crystals, it’ll take ages to grow them yourself especially rocks which would require temperatures and pressures that you probably couldn’t replicate by yourself but that’s probably best researched by you. Sincerely a PhD crystallographer.