I do, it is really beautiful, on the rider or on the horse!
I do! I have some on my jacket, on my helmet and on some of my dressage saddle pads. It is my girly touch :p
For the moment I don't own horse riding clothing or equipment with rhinestones but if I did dressage competition, I would definitely buy a jacket with some rhinestones. I like them on jackets, helmets and saddle pads when it remains discreet :)
I never used to like them, but I've grown to love them! I don't like to go overboard, but I have some on my helmet. I also think they also look good on brow bands, and occasionally certain tendon boots and saddle pads. I won't judge people who wear loads though, their choice (plus it usually looking great) :)
As a dressage rider, I do like a bit of bling on some items, but I like it to be discrete, like a nice stockpin, things like that.
I wouldn't buy something with rhinestones for me but it can be pretty on girls if it's discreet :)