I got it from this guy.
http://wow.allakhazam.com/db/mob.html?wmob=7852
Not sure of the time but I picked it up around 8:30am PST.
And as for the Gem-studded belt recipe. The timer is about 15-20 minutes. I camped this guy,
http://wow.allakhazam.com/db/mob.html?wmob=2699
for an hour and a half one day. And every 15-20 minutes, either the Gem-studded belt pattern would pop or the Shadowskin Gloves pattern would....Not entirely sure though, I only scored the Glove pattern three times, 1 for me, 1 for guildie, and one to sell at AH^^;
Just take timing and constantly checking any and all vendors as you go^^
Just my Two cents^^
Dynnllia--Dragonmaw--Lv47 Rogue--
--Guild Member of Defiant Retribution--