Hall of Gemstone Tweet Sorry, we are not purchasing this product at this time. Buy This Product Details Color: Green Card Text: At the beginning of each player's upkeep, that player chooses a color. Until end of turn, lands tapped for mana produce mana of the chosen color instead of any other color. Rarity: R Cost: 1GG Card Type: Enchantment Name: Hall of Gemstone Finish: Regular Set Name: Mirage