We’ll give different advice here, because the gems market is highly volatile. It can make more money than almost any other profession if you watch the market carefully and look for huge spikes in cost. Gems tend to flood the market during beginning to middle of a patch cycle, and spike in value around the end-middle when the content drought makes the market more scarce. It is advised in particular to watch the Tidal Amethyst gemstone, which is very economical to craft and has been known to spike at upwards of 8000%. With gems, it is less about rate per hour and more about how long you can hold before selling. Good luck!
Yes, that is easy, but it's not quick. Further down in my comments to OP I detailed the GIO farm, and reasonable yield expectations. I looked up a few guides/videos before commenting and most of them estimate a yield beween 800-1,000 GIO/hour. That lines up with my past experience with it as well. That'd be, taking the high yield end, 4.2 hours to farm the GIO for one toon's monthly needs.
It's not about me, it's about people having trouble making gold with BfA professions for example, or having herb prices drop too low to make it worth the effort, I just meant to say there are other ways of making gold. I personnally make most my gold out of BfA for example, so I wanted to point out it's not a necessary thing to stick to the current extension.
The game is based on the Warcraft series of RTS games first released in the mid 1990s. WoW expanded on the early Warcraft single player franchise and is now a vibrant multiplayer world, where players may engage in roleplaying, PvE, PvP, dungeon instances, battlegrounds, arenas, and raids. There are lots of challenges in WOW, and WOW gold plays an important role to help players to succeed in these challenges. 

As the battle for Darkshore begins, both the Alliance and Horde are blindsided by a new development: High Overlord Saurfang, who had been defeated and captured in the Battle of Lordearon, has suddenly escaped Alliance captivity and is on the run. Sylvanas sends Horde Champions to track Saurfang down, ostensibly to extract him. However, it quickly becomes apparent that the search party is in fact an assassination squad, as Sylvanas suspects Saurfang of colluding with the Alliance in an attempt to dethrone her. While some Horde champions choose to side with Saurfang and help him escape the assassins, other champions remain loyal to Sylvanas and report Saurfang's and the dissenting champions' treachery to her.

Like I said, engineering is the best when you aren't worried about making gold. The Loot-a-rang is super useful, nitro-boosts are nice when they don't fail, and the glider cape enchant is nice too... you get wormholes to Pandaria, Draenor (make sure you have a glider), Legion, and Argus (as well as a couple old world teleport locations)...Jeeves (and to a lesser extent Reeves) and MOLL-E are also super useful (bank and mail access anywhere, repairs, etc.).
Blacksmith, Tailoring, Leatherworking all can create their own BoP gear like before with Blacksmithing able to potentially create indestructible versions and can repair in the field instantly (not that big), while Tailoring gets specific cloak enchants with some unique effects like not being able to to be dazed which is going to be very useful for Tailoring/Herbalists.
That's where i'm at now. I got into it late. I had 40k to start. Sold fish up to about 100k total starting capital. Started making and selling decks when they were going for 80-200k on my server. Morons have repeatedly undercut decks by 30-60k at a time even after the market has been reset (not by me) multiple times. Now the decks are 25-80k... I did manage to make 3.5m gross in the last 2 weeks. Now the individual cards are selling for MUCH less than the decks so I may stop crafting myself and just start buying the individuals... idk where to go from there though. Do you think the decks will hold any value moving forward? I'm kind of hoping for something similar to obliterum in legion to increase the ilvl and keep them relevant.