Thursdays update bought fantastic update to the Shilo Village underground gem mine.
There are now a tonne of gem rocks leading in a circuit to a deposit box.
With 70 mining and a dragon pickaxe I'm able to get 50k XP/H and at least 400k-600k GP/H.
(15-30k per inv, 20-30 invs per hour)
It's far less intensive than Blast Mining and more profitable.
Requirements:
Dragon Pickaxe
Charged amuet of glory (Makes gems mine in a few ticks)
Karamja hard diary (Stat reqs below)
44 Runecrafting
30 Cooking
34 Woodcutting
50 Strength
53 Agility
50 Thieving
52 Mining
42 Ranged
100 Combat
50 Slayer
(I post some screenies to make this look more professional but Lightshot isn't working ATM)