Q:When trying to access the higher spellgems is this based on civilisation level or region level? Is the below correct?
Civ level 1-5 Spell gem level 1
Civ level 6 - 10 Spell gem level 2
Civ level 11 - 15 Spell gem level 3
Does this increase every 5 levels?
The lvl of the area the vein is in is what matters.
Ranks go up by one every 5 lvls with the rank 1 gem only being available until vein lvl 4, however.
So it's as follows:
vein in area lvl 1-4: gem lvl 1
vein in area lvl 5-9: gem lvl 2
vein in area lvl 10-14: gem lvl 3
...
What you shouldn't forget is that the lvl of the vein isn't necessarily the lvl of the tile on the world map (with
"highest" underground areas always being 1 lvl above the lvl of the world map tile).