Just did some testing again to see if making Artificer Enhancements was just as annoying as before. Seems to be the case, sadly.
I didn't want to waste precious metals, so tried my test on tin bars and Moonstone Necklaces. I made 10 of them, and salvaged them all. I got 2 Moonstones returned, so made 2 more necklaces. That's 12 Moonstone Necklaces. Other than some returned tin bars and metallic bits, I got 9 Gemstone Fragments. Almost enough to make one Glowing Manastone (increases max mana by 100 for 1 hour).
So you need to salvage 12-15 necklaces (any recipe that includes a gem in it) to get enough gem fragments to create the salvaged gem (or level equivalent gem) required for the enhancement recipe.
It may be worthwhile only at lvl 50 or if you are in a raiding guild. Otherwise, for general use (or to use while leveling up), I personally couldn't be bothered. It's too little return for too many salvaged items for me.