diff --git a/.gitattributes b/.gitattributes
index f4d04e693b6..4873c217b06 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -5119,6 +5119,7 @@ forge-gui/res/cardsfolder/h/halcyon_glaze.txt svneol=native#text/plain
 forge-gui/res/cardsfolder/h/halimar_depths.txt svneol=native#text/plain
 forge-gui/res/cardsfolder/h/halimar_excavator.txt svneol=native#text/plain
 forge-gui/res/cardsfolder/h/halimar_wavewatch.txt svneol=native#text/plain
+forge-gui/res/cardsfolder/h/hall_of_gemstone.txt -text
 forge-gui/res/cardsfolder/h/hall_of_the_bandit_lord.txt -text
 forge-gui/res/cardsfolder/h/hallow.txt -text
 forge-gui/res/cardsfolder/h/hallowed_burial.txt svneol=native#text/plain
diff --git a/forge-gui/res/cardsfolder/h/hall_of_gemstone.txt b/forge-gui/res/cardsfolder/h/hall_of_gemstone.txt
new file mode 100644
index 00000000000..b24a4e36b13
--- /dev/null
+++ b/forge-gui/res/cardsfolder/h/hall_of_gemstone.txt
@@ -0,0 +1,10 @@
+Name:Hall of Gemstone
+ManaCost:1 G G
+Types:World Enchantment
+T:Mode$ Phase | Phase$ Upkeep | ValidPlayer$ Player | Execute$ TrigChoose | TriggerZones$ Battlefield | TriggerDescription$ 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.
+SVar:TrigChoose:AB$ ChooseColor | Cost$ 0 | Defined$ TriggeredPlayer | AILogic$ MostProminentInActivePlayerHand | SubAbility$ DBEffect
+SVar:DBEffect:DB$ Effect | ReplacementEffects$ ReplaceChosen | SVars$ ProduceChosen
+SVar:ReplaceChosen:Event$ ProduceMana | ActiveZones$ Command | ValidCard$ Land | ManaReplacement$ ProduceChosen | Description$ Lands tapped for mana produce mana of the chosen color instead of any other color.
+SVar:ProduceChosen:Colorless->Chosen & U->Chosen & B->Chosen & R->Chosen & G->Chosen & W->Chosen
+SVar:Picture:http://www.wizards.com/global/images/magic/general/hall_of_gemstone.jpg
+Oracle: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.
diff --git a/forge-gui/src/main/java/forge/ai/ComputerUtilCard.java b/forge-gui/src/main/java/forge/ai/ComputerUtilCard.java
index 91fa2e7a086..7ee6047e54e 100644
--- a/forge-gui/src/main/java/forge/ai/ComputerUtilCard.java
+++ b/forge-gui/src/main/java/forge/ai/ComputerUtilCard.java
@@ -867,6 +867,9 @@ public class ComputerUtilCard {
             else if (logic.equals("MostProminentAttackers") && game.getPhaseHandler().inCombat()) {
                 chosen.add(ComputerUtilCard.getMostProminentColor(game.getCombat().getAttackers(), colorChoices));
             }
+            else if (logic.equals("MostProminentInActivePlayerHand")) {
+                chosen.add(ComputerUtilCard.getMostProminentColor(game.getPhaseHandler().getPlayerTurn().getCardsIn(ZoneType.Hand), colorChoices));
+            }
             else if (logic.equals("MostProminentKeywordInComputerDeck")) {
                 List<Card> list = ai.getAllCards();
                 int m1 = 0;
diff --git a/forge-gui/src/main/java/forge/game/replacement/ReplacementHandler.java b/forge-gui/src/main/java/forge/game/replacement/ReplacementHandler.java
index 69bee00a4d7..bce091669ad 100644
--- a/forge-gui/src/main/java/forge/game/replacement/ReplacementHandler.java
+++ b/forge-gui/src/main/java/forge/game/replacement/ReplacementHandler.java
@@ -25,6 +25,7 @@ import java.util.Map;
 
 import org.apache.commons.lang3.StringUtils;
 
+import forge.card.MagicColor;
 import forge.game.Game;
 import forge.game.GameLogEntryType;
 import forge.game.ability.AbilityFactory;
@@ -219,7 +220,12 @@ public class ReplacementHandler {
             final Player player1 = (Player) runParams.get("Player");
             final String rep = (String) runParams.get("Mana");
             // Replaced mana type
-            manaAb.getManaPart().setManaReplaceType(replacementEffect.getHostCard().getSVar(mapParams.get("ManaReplacement")));
+            final Card repHost = replacementEffect.getHostCard();
+            String repType = repHost.getSVar(mapParams.get("ManaReplacement"));
+            if (repType.contains("Chosen") && !repHost.getChosenColor().isEmpty()) {
+                repType = repType.replace("Chosen", MagicColor.toShortString(repHost.getChosenColor().get(0)));
+            }
+            manaAb.getManaPart().setManaReplaceType(repType);
             manaAb.getManaPart().produceMana(rep, player1, manaAb);
         } else {
             player.getController().playSpellAbilityNoStack(effectSA, true);