Yes.

Golds are the most rare, Silvers are the second rarest, and Base cards are the least rare. All Base cards are unlocked through gameplay for free and are the easiest to obtain.

Silver cards can be earned via Ranked Rewards (i.e. ranking highly on the leaderboard), winning on Conquest mode, as well as the Premium Skypass.

All Gold cards are earned via Conquest (by winning 3 games in a row) to the exceptionally skilled players. Every week, a different set of unique cards will be available as Golds to be won in Conquest. At the end of that week, those specific Gold cards will never be minted again.