crystals as in gemstones? if yes then :@Downtown in most of the jewellery stores, you can find them at @Over The Rainbow but i'm not sure if they're open rn since it's considered a yoga studio, there's also a store, it's in a small alley right next to the @Istiklal Library Co. in swefieh, but i honestly don't remember the name.
Thriftshops around @Downtown don't usually advertise themselves over the internet, you'll have to go and have a walk around there to find what you're looking for