Guild Master Silver Coin

[Milithistorian]

is the only way to get them through loffy?

it seems really slow if you're trying to get lvl 80 skill gem

[Panpeito]

atm, yes its the only way. in the past they had events that dropped them (saints haven defense) but those events are rather sparse.

[Cloud]

you can buy them from the ladder shop for 20 points each

up to 20 per week