these consumables will be appearing in patch 5.1, and can be used to upgrade any pet to rare quality (there will also be a polished battle-stone which upgrades pets to uncommon, but meh). according to the patch notes,
"players will have a very small chance to obtain a general purpose flawless battle-stone after winning a match against wild pets; defeating
higher level opponents increases the chances of obtaining a stone. these valuable items are not soulbound, and can be sold on the auction house."
there will also be pet family-specific versions: flawless elemental battle-stone, flawless mechanical battle-stone, etc. these stones can only be used to upgrade a pet of that particular family, are soulbound, and are won not by fighting local pets but rather will show up in the sack of pet supplies you get from defeating the npc pet tamers.
different, but also interesting.
so, how should we respond to the introduction of these stones when 5.1 goes live? the answer is, of course, however the hell you want. take a team of low-level but high-performance pets out on the road to farm the locals for stones to sell on the auction house? go for it. try to hit every pet trainer daily, every day? go for it. pretty much the same as before, and sometimes say "oh look, a stone"? go for it. there is no wrong way to play.
me, i'm not that excited about the stones, because i already have more rares than i know what to do with. there are a few pets that i like enough that i'd be willing to spend a non-soulbound stone on to upgrade (depending on how the prices settle out, i might even buy the stones). the upgrade priority queue will be sleepy willy, personal world destroyer, creepy crate, sinister squashling, mechanical squirrel, and the enchanted broom (unless i change my mind). after these, i'll probably give away any unbound stones i get to family and friends. i've found my interest in hitting the dailies kind of comes and goes, depending on what else i have going on, and that will probably stay the same. any stones i get from these will probably be applied after careful deliberation of at least three or four seconds.
any pets you folks are particularly excited about being able to give the rarification treatment to?