Gemstone Mine is a rare Land card from Dominaria Remastered (DMR), collector number 395. Current market price: $2.64 (foil $5.35), TCGplayer market prices via Scryfall.
This land enters with three mining counters on it. {T}, Remove a mining counter from this land: Add one mana of any color. If there are no mining counters on this land, sacrifice it.