Spitfire Sapphire is one of those rare gems in WoW that makes crafting high-end gear feel extra rewarding. I spent weeks figuring out the best ways to get it, and honestly, farming it isn't as straightforward as some other gems. The most reliable method is prospecting 'Draenic Stone' from Warlords of Draenor zones—I had the best luck with the 'Nagrand' ore nodes. It's a bit of a grind, but if you're an alchemist or jewelcrafter, it's worth stockpiling. Another option is checking the Auction House, but prices can be wild depending on your server's economy.
If you're into dungeons, some Warlords of Draenor bosses drop it occasionally, though the rates aren't great. I remember running 'Bloodmaul Slag Mines' a few times just for a chance at it. For a less RNG-heavy approach, trading with other players or joining a guild with dedicated crafters might save you time. Either way, patience is key—this gem doesn't just fall into your lap!