i know for pve for yellow its smooth radiance, red = potent verm, blue = piercing wild jade. is there a similar recommendation for pvp gear as well, in terms of pvp power, int, crit/haste for pvp frost?
What sort of PvP are you doing? This will depend on what you're doing, what your partners are, and other factors. If you're running random BGs, match all your sockets and base which choices you make on what you feel you need most. As a general rule, PvP power is the most potent offensive stat, Intellect will give you offense and also increase your shields, Resilience is (obviously) your best defensive stat. I've personally favored Resil over second stats because I can't necessarily count on having a healer available to me.
In Arenas, people take more hardline stances and build their gear around their comp. There's multiple successful approaches.
Yeah, I think the best advice you can get (even thought it's pretty squishy) is to gem for what you currently feel like you're missing. If you feel like you need tighter windows to get off cast bars, go Haste in yellow slots; if you think you want bigger shatters, go Mastery, if you want pure offense, prioritize PvP power, and so on. Just make sure you're always matching your sockets, the bonuses are basically always worth it.