I was doing gems in week 1. As soon as you get hammer mastery to 4. You just buy a gem tool, I advise a diamond hammer to strip mine (leave it at home at first).
Get a beacon and some fuel, make sure you have a plot or preferably 2 spare. Buy an atlas + gem of the type you want, go to the world with the gems via the transport hub to that world, and setup a beacon nearby it, fuel it.
Then find a good spot on the atlas and dig to it (whatever altitude on here)
MEGA THREAD: Gem Locations (After March 2017 Resource Distribution) - This is the only risky bit, I also advise some aggro reduction on your gatherer or using a hunter alt to setup the beacon and run/tank any hits.
Set up the second beacon safe underground, make sure there is room above/around it to warp in. Now when you want gems you go to that world through the transfer hub and then go to sanctum, then warp to your new gem beacon. Which costs 100 coins to warp to a point on the same world. If you are clever you’ve set the beacon near the transfer hub too, so its 100 out of your mine as well. 200 per trip. Which is the price of one gem sold on the market. That’s your transport cost until you have a portal setup, which is perfectly viable if you stay out there awhile, you’ll get 40-150 gems per trip strip mining for an hour. - You could also walk there, I did at first and just mined down, you can find some nice leftover meteor ore but its more dangerous obviously to walk there each time.
To vastly improve your newbie yield get the tool durability skill line and invest in persistant pies. That diamond hammer now has 90% more durability with 50% skills + 40% pie buff. As long as you are strip mining underground, not in caves your low level won’t matter. Its not as profitable as caving but it still works, I still do it in nice areas.
Oh and if you go with your hunter at first, don’t forget to add your gatherer to the beacon permissions 
- Also good locations need to take into account the number of other players portals on the location heh.