I collect 800 gems/month as F2P, as 10 pulls is 2600, that is around 3 pulls/month.
Raid/monster chest is 3 gems on average. 2 monster chests + 2 raid chests per day.
(360 gems/month).
Mystic vision around 1-2. Three MV = 4 gems per day.
(120gems/month)
Titan around 5 but not always killed. 5 killed each 6 titans = 24 killed titans/month.
(120 gems/month)
There are also collect gems I & II each once a week. Collect gems I = 1+3+6=10; collect gems II = 3+6+9=18.
(112 gems/month)
And elemental chest, usually 3 chests per month with each chest contain 30 gems on average.
(90 gems/month)
Still not counting war loot/chest.