"I think what Mateusz Konieczny
was getting at is that shop=crystal is not proper/standard tag for OSM"

or at least it is not usual and meaning seems unclear to me (I have seen shops selling crystals that were

- (1) jewellery
- (2) supposedly cancer-curing crystals

In theory shop selling jewellery can be also selling industrial supplies or raw materials for jewellery or some class of chemical feedstock.

"Not really sure why you're suggesting it doesn't exist, but I'll assume you're just going through all the options ;)."

yes, many of shops with unusual tags turned out to be mapped long time ago or by really new mappers and were not actually existing (or were tagging mistakes, I seen shop=sourvey that was supposed to be source=survey)