So, I recently bought a fluorite bullet cut pendant, and, without knowing it was bad to do so, left it in water for about 20 minutes.
Did I goof? It doesn't look physically damaged...but is it as strong as before?
Yeah, it's just as strong as it before. Some crystals are not supposed to go in the water because they dissolve, or other reasons. Such as Fluorite, which is not supposed to go in the sunlight or water because of fading in color and dissolving.