I have had bad luck with it. I get undercut by crazy amounts takes me forever to sell them all
simply buy the ores when they are cheap and sell the gems during peak time (weekends and raiding days).
if your server isnt extremely empty, this will work since the ore prices will skyrocket on peak times and you can still sell them for high profit by undercutting. key is to know how much a gem costs you.
if you however expect to sell all gems on of days by posting them once midday you cannot expect much.
my biggest profits come on tuesdays, when everyone can grind more conquest and are upgrading their pvp gear!
on my server tuesday is the "buy all the mats" day and on wed/thurs comes the high profit (people here tend to cap and do raids asap, so gems will sell mostly on these days)
Mal'ganius US here;
I probably used less than 200 stacks yesterday.
Walked in with 3k gold - Walked out with 6k.
Back a few months ago I could make 100k in profit or more from just jc and ench on a tue night, today it is just a fraction of that.
Also depends on if your enchanter and JC are the same character. IMHO.. the enchanting part of it is gone. Enchanting mats and enchants are just too cheap to be worth it. Probably because of our ability to ´upgrade´ dusts this expansion. In my case, it definitely wasn´t worth sending jewelry to my enchanter.
I am just cutting common gems, selling the perfects and vendoring the normals. The agi rings sell good, so I always keep about 5 of them on hand to sell (ie, I don´t cut the purple gems).
I made a ton of gold selling the gems I got from learning new gems.
It is a bit random and it will take a few weeks because you can get so many gems (and strictly speaking it cost more since it takes 3 gems for 2 random gems) but if you can farm the Zandalari Warbringers you will get more ore then you can possibly use.
It works very well on my server.
Ever since the removal of PvP Resilence on gear, PvP gems went up from 30g to 200g+ on my server, with all other gems evening out at about 100g a gem. Life is good..
I'm so glad I spent the weekend prospecting. I've sold gems for more than 100k on two realms combined today.