diff --git a/migrations/20140831_increase_gems_for_previous_contributions.js b/migrations/20140831_increase_gems_for_previous_contributions.js
new file mode 100644
index 0000000000..694409a5b7
--- /dev/null
+++ b/migrations/20140831_increase_gems_for_previous_contributions.js
@@ -0,0 +1,126 @@
+// IMPORTANT:
+//
+// run like this to capture all output:
+//
+// node 20140831_increase_gems_for_previous_contributions.js  > 20140831_increase_gems_for_previous_contributions_output.txt
+
+
+var migrationName = '20140831_increase_gems_for_previous_contributions';
+
+/**
+ * https://github.com/HabitRPG/habitrpg/issues/3933
+ * Increase Number of Gems for Contributors
+ * author: Alys (d904bd62-da08-416b-a816-ba797c9ee265)
+ * 
+ * Increase everyone's gems per their contribution level.
+ * Originally they were given 2 gems per tier.
+ * Now they are given 3 gems per tier for tiers 1,2,3
+ *                and 4 gems per tier for tiers 4,5,6,7
+ * So that means an EXTRA 1 for tier 1,
+ *                        2 for tier 2,
+ *                        3 for tier 3,
+ *                        5 for tier 4,
+ *                        7 for tier 5,
+ *                        9 for tier 6,
+ *                       11 for tier 7,
+ *                       11 for tier 8 (moderators = tier 7 + admin privileges),
+ *                     none for tier 9 (staff)
+ */
+
+var mongo = require('mongoskin');
+var _ = require('lodash');
+
+
+var dbUsers = mongo.db('localhost:27017/habitrpg?auto_reconnect').collection('users');
+
+
+var query = {
+    'contributor.level': {$gt: 0, $lt: 9},
+    'migration': {$ne: migrationName}
+};
+
+var fields = {
+    'migration':1,
+    'contributor.level':1,
+    'balance':1
+};
+
+var userResults = {}; // each key is a UUID, each value is a string
+                      // describing what changed for that user
+
+console.warn('Updating users...');
+var progressCount = 50;
+var count = 0;
+dbUsers.findEach(query, fields, function(err, user) {
+    if (err) { return exiting(1, 'ERROR! ' + err); }
+    if (!user) {
+        console.warn('All users found. Fetching final balances...');
+        return fetchFinalBalances();
+    }
+    count++;
+
+    var set = {'migration': migrationName};
+
+    var tier = user.contributor.level;
+    var extraGems = tier; // tiers 1,2,3
+    if (tier > 3)  { extraGems = 3 + (tier - 3) * 2; }
+    if (tier == 8) { extraGems = 11; }
+    extraBalance = extraGems / 4;
+    set['balance'] = user.balance + extraBalance;
+
+    // Capture current state of user:
+    userResults[user._id] =
+        user._id + ' ' + ':\n' +
+        '  contrib tier          :  ' + tier + '\n' +
+        '  balance before        :  ' + user.balance + '\n' +
+        '  balance (gems) added  :  ' + extraBalance + ' (' +
+                                        extraGems + ')' + '\n' +
+        '  expected balance after:  ' + (user.balance + extraBalance) + '\n';
+
+    // Update user:
+    dbUsers.update({_id:user._id}, {$set:set, $inc:{_v:1}});
+    if (count%progressCount == 0) console.warn(count + ' ' + user._id);
+});
+
+
+function fetchFinalBalances() {
+    var query = {_id: {$in: Object.keys(userResults)}};
+    var fields = {
+        'balance':1,
+    };
+
+    var count1 = 0;
+    dbUsers.findEach(query, fields, function(err, user) {
+        if (err) { return exiting(1, 'ERROR! ' + err); }
+        if (!user) {
+            console.warn('All final balances found.');
+            return displayData();
+        }
+        count1++;
+        userResults[user._id] = userResults[user._id] +
+            user._id + ' ' + ':\n' +
+            '  actual balance after  :  ' + user.balance + '\n';
+        if (count1%progressCount == 0) console.warn(count1 + ' ' + user._id);
+    });
+}
+
+
+function displayData() {
+    _.each(userResults, function(text, uuid) {
+        console.log(text); // text contains uuid
+    });
+    console.log('\n' + count +
+            ' users processed (should be roughly 335 according to the Hall)\n');
+    return exiting(0);
+}
+
+
+function exiting(code, msg) {
+    code = code || 0; // 0 = success
+    if (code && !msg) { msg = 'ERROR!'; }
+    if (msg) {
+        if (code) { console.error(msg); }
+        else      { console.log(  msg); }
+    }
+    process.exit(code);
+}
diff --git a/src/controllers/hall.js b/src/controllers/hall.js
index d3a2796476..6fc104b0a1 100644
--- a/src/controllers/hall.js
+++ b/src/controllers/hall.js
@@ -55,9 +55,17 @@ api.updateHero = function(req,res,next) {
     function(member, cb){
       if (!member) return res.json(404, {err: "User not found"});
       member.balance = req.body.balance || 0;
-      if (req.body.contributor.level > (member.contributor && member.contributor.level || 0)) {
+      newTier = req.body.contributor.level; // tier = level in this context
+      oldTier = member.contributor && member.contributor.level || 0;
+      if (newTier > oldTier) {
         member.flags.contributor = true;
-        member.balance += (req.body.contributor.level - (member.contributor.level || 0))*.5 // +2 gems per tier
+        gemsPerTier = {1:3, 2:3, 3:3, 4:4, 5:4, 6:4, 7:4, 8:0, 9:0}; // e.g., tier 5 gives 4 gems. Tier 8 = moderator. Tier 9 = staff
+        tierDiff = newTier - oldTier; // can be 2+ tier increases at once
+        while (tierDiff) {
+          member.balance += gemsPerTier[newTier] / 4; // balance is in $
+          tierDiff--;
+          newTier--; // give them gems for the next tier down if they weren't aready that tier
+        }
       }
       member.contributor = req.body.contributor;
       member.purchased.ads = req.body.purchased.ads;
@@ -74,4 +82,4 @@ api.updateHero = function(req,res,next) {
     if (err) return next(err);
     res.json(204);
   })
-}
\ No newline at end of file
+}