diff --git a/Source/Scene/Cesium3DTileStyle.js b/Source/Scene/Cesium3DTileStyle.js
index ebe58488f23a..c4987a1fff86 100644
--- a/Source/Scene/Cesium3DTileStyle.js
+++ b/Source/Scene/Cesium3DTileStyle.js
@@ -40,11 +40,11 @@ define([
      * @example
      * tileset.style = new Cesium.Cesium3DTileStyle({
      *     color : {
-     *         conditions : {
-     *             '${Height} >= 100' : 'color("purple", 0.5)',
-     *             '${Height} >= 50' : 'color("red")',
-     *             'true' : 'color("blue")'
-     *         }
+     *         conditions : [
+     *             ['${Height} >= 100', 'color("purple", 0.5)'],
+     *             ['${Height} >= 50', 'color("red")'],
+     *             ['true', 'color("blue")']
+     *         ]
      *     },
      *     show : '${Height} > 0',
      *     meta : {
diff --git a/Source/Scene/Cesium3DTileset.js b/Source/Scene/Cesium3DTileset.js
index e80c8f1d8a8a..fcc16a681918 100644
--- a/Source/Scene/Cesium3DTileset.js
+++ b/Source/Scene/Cesium3DTileset.js
@@ -500,11 +500,11 @@ define([
          * @example
          * tileset.style = new Cesium.Cesium3DTileStyle({
          *    color : {
-         *        conditions : {
-         *            '${Height} >= 100' : 'color("purple", 0.5)',
-         *            '${Height} >= 50' : 'color("red")',
-         *            'true' : 'color("blue")'
-         *        }
+         *        conditions : [
+         *            ['${Height} >= 100', 'color("purple", 0.5)'],
+         *            ['${Height} >= 50', 'color("red")'],
+         *            ['true' : 'color("blue")']
+         *        ]
          *    },
          *    show : '${Height} > 0',
          *    meta : {
diff --git a/Source/Scene/ConditionsExpression.js b/Source/Scene/ConditionsExpression.js
index 986467e1e23d..c8c6138dfb90 100644
--- a/Source/Scene/ConditionsExpression.js
+++ b/Source/Scene/ConditionsExpression.js
@@ -32,11 +32,11 @@ define([
      * @example
      * var expression = new Cesium.Expression({
      *     expression : 'regExp("^1(\\d)").exec(${id})',
-     *     conditions : {
-     *         '${expression} === "1"' : 'color("#FF0000")',
-     *         '${expression} === "2"' : 'color("#00FF00")',
-     *         'true' : 'color("#FFFFFF")'
-     *     }
+     *     conditions : [
+     *         ['${expression} === "1"', 'color("#FF0000")'],
+     *         ['${expression} === "2"', 'color("#00FF00")'],
+     *         ['true', 'color("#FFFFFF")']
+     *     ]
      * });
      * expression.evaluateColor(feature, result); // returns a Cesium.Color object
      *
@@ -78,23 +78,25 @@ define([
     function setRuntime(expression) {
         var runtimeConditions = [];
         var conditions = expression._conditions;
-        var exp = expression._expression;
-        var length = conditions.length;
-        for (var i = 0; i < length; ++i) {
-            var statement = conditions[i];
-            var cond = String(statement[0]);
-            var condExpression = String(statement[1]);
-            if (defined(exp)) {
-                cond = cond.replace(expressionPlaceholder, exp);
-                condExpression = condExpression.replace(expressionPlaceholder, exp);
-            } else {
-                cond = cond.replace(expressionPlaceholder, 'undefined');
-                condExpression = condExpression.replace(expressionPlaceholder, 'undefined');
+        if (defined(conditions)) {
+            var exp = expression._expression;
+            var length = conditions.length;
+            for (var i = 0; i < length; ++i) {
+                var statement = conditions[i];
+                var cond = String(statement[0]);
+                var condExpression = String(statement[1]);
+                if (defined(exp)) {
+                    cond = cond.replace(expressionPlaceholder, exp);
+                    condExpression = condExpression.replace(expressionPlaceholder, exp);
+                } else {
+                    cond = cond.replace(expressionPlaceholder, 'undefined');
+                    condExpression = condExpression.replace(expressionPlaceholder, 'undefined');
+                }
+                runtimeConditions.push(new Statement(
+                    new Expression(cond),
+                    new Expression(condExpression)
+                ));
             }
-            runtimeConditions.push(new Statement(
-                new Expression(cond),
-                new Expression(condExpression)
-            ));
         }
 
         expression._runtimeConditions = runtimeConditions;
diff --git a/Source/Scene/Expression.js b/Source/Scene/Expression.js
index 1867181bce2c..9ba8dc1607c4 100644
--- a/Source/Scene/Expression.js
+++ b/Source/Scene/Expression.js
@@ -118,7 +118,11 @@ define([
      */
     Expression.prototype.evaluate = function(feature) {
         scratchColorIndex = 0;
-        return this._runtimeAst.evaluate(feature);
+        var result = this._runtimeAst.evaluate(feature);
+        if (result instanceof Color) {
+            return Color.clone(result);
+        }
+        return result;
     };
 
     /**
diff --git a/Specs/Scene/Cesium3DTileStyleSpec.js b/Specs/Scene/Cesium3DTileStyleSpec.js
index 3509c71f332c..34c479572ac5 100644
--- a/Specs/Scene/Cesium3DTileStyleSpec.js
+++ b/Specs/Scene/Cesium3DTileStyleSpec.js
@@ -148,10 +148,10 @@ defineSuite([
 
     it ('sets color value to conditional', function() {
         var jsonExp = {
-            conditions : {
-                '${height} > 2' : 'color("cyan")',
-                'true' : 'color("blue")'
-            }
+            conditions : [
+                ['${height} > 2', 'color("cyan")'],
+                ['true', 'color("blue")']
+            ]
         };
 
         var style = new Cesium3DTileStyle({
@@ -295,11 +295,11 @@ defineSuite([
         var style = new Cesium3DTileStyle({
             "color" : {
                 "expression" : "regExp('^1(\\d)').exec(${id})",
-                "conditions" : {
-                    "${expression} === '1'" : "color('#FF0000')",
-                    "${expression} === '2'" : "color('#00FF00')",
-                    "true" : "color('#FFFFFF')"
-                }
+                "conditions" : [
+                    ["${expression} === '1'", "color('#FF0000')"],
+                    ["${expression} === '2'", "color('#00FF00')"],
+                    ["true", "color('#FFFFFF')"]
+                ]
             }
         });
         expect(style.show.evaluate(feature1)).toEqual(true);
@@ -311,14 +311,14 @@ defineSuite([
         var style = new Cesium3DTileStyle({
             "color" : {
                 "expression" : "${Height}",
-                "conditions" : {
-                    "(${expression} >= 1.0)  && (${expression} < 10.0)" : "color('#FF00FF')",
-                    "(${expression} >= 10.0) && (${expression} < 30.0)" : "color('#FF0000')",
-                    "(${expression} >= 30.0) && (${expression} < 50.0)" : "color('#FFFF00')",
-                    "(${expression} >= 50.0) && (${expression} < 70.0)" : "color('#00FF00')",
-                    "(${expression} >= 70.0) && (${expression} < 100.0)" : "color('#00FFFF')",
-                    "(${expression} >= 100.0)" : "color('#0000FF')"
-                }
+                "conditions" : [
+                    ["(${expression} >= 1.0)  && (${expression} < 10.0)", "color('#FF00FF')"],
+                    ["(${expression} >= 10.0) && (${expression} < 30.0)", "color('#FF0000')"],
+                    ["(${expression} >= 30.0) && (${expression} < 50.0)", "color('#FFFF00')"],
+                    ["(${expression} >= 50.0) && (${expression} < 70.0)", "color('#00FF00')"],
+                    ["(${expression} >= 70.0) && (${expression} < 100.0)", "color('#00FFFF')"],
+                    ["(${expression} >= 100.0)", "color('#0000FF')"]
+                ]
             }
         });
         expect(style.show.evaluate(feature1)).toEqual(true);
@@ -329,14 +329,14 @@ defineSuite([
     it ('applies color style with conditional', function() {
         var style = new Cesium3DTileStyle({
             "color" : {
-                "conditions" : {
-                    "(${Height} >= 100.0)" : "color('#0000FF')",
-                    "(${Height} >= 70.0)" : "color('#00FFFF')",
-                    "(${Height} >= 50.0)" : "color('#00FF00')",
-                    "(${Height} >= 30.0)" : "color('#FFFF00')",
-                    "(${Height} >= 10.0)" : "color('#FF0000')",
-                    "(${Height} >= 1.0)" : "color('#FF00FF')"
-                }
+                "conditions" : [
+                    ["(${Height} >= 100.0)", "color('#0000FF')"],
+                    ["(${Height} >= 70.0)", "color('#00FFFF')"],
+                    ["(${Height} >= 50.0)", "color('#00FF00')"],
+                    ["(${Height} >= 30.0)", "color('#FFFF00')"],
+                    ["(${Height} >= 10.0)", "color('#FF0000')"],
+                    ["(${Height} >= 1.0)", "color('#FF00FF')"]
+                ]
             }
         });
         expect(style.show.evaluate(feature1)).toEqual(true);
diff --git a/Specs/Scene/Cesium3DTilesetSpec.js b/Specs/Scene/Cesium3DTilesetSpec.js
index 64986b4f83c4..974047751629 100644
--- a/Specs/Scene/Cesium3DTilesetSpec.js
+++ b/Specs/Scene/Cesium3DTilesetSpec.js
@@ -1177,10 +1177,10 @@ defineSuite([
             // ${id} < 10 will always evaluate to true
             tileset.style = new Cesium3DTileStyle({
                 color : {
-                    conditions : {
-                        '${id} < 10' : 'color("red")',
-                        'true' : 'color("blue")'
-                    }
+                    conditions : [
+                        ['${id} < 10', 'color("red")'],
+                        ['true', 'color("blue")']
+                    ]
                 }
             });
             var color = scene.renderForSpecs();
@@ -1192,10 +1192,10 @@ defineSuite([
             // ${id}>= 10 will always evaluate to false
             tileset.style = new Cesium3DTileStyle({
                 color : {
-                    conditions : {
-                        '${id} >= 10' : 'color("red")',
-                        'true' : 'color("blue")'
-                    }
+                    conditions : [
+                        ['${id} >= 10', 'color("red")'],
+                        ['true', 'color("blue")']
+                    ]
                 }
             });
             color = scene.renderForSpecs();
diff --git a/Specs/Scene/ConditionsExpressionSpec.js b/Specs/Scene/ConditionsExpressionSpec.js
index aa18b8ecb1d7..e7100876dccd 100644
--- a/Specs/Scene/ConditionsExpressionSpec.js
+++ b/Specs/Scene/ConditionsExpressionSpec.js
@@ -18,37 +18,37 @@ defineSuite([
     };
 
     var jsonExp = {
-        conditions : {
-            '${Height} > 100' : 'color("blue")',
-            '${Height} > 50' : 'color("red")',
-            'true' : 'color("green")'
-        }
+        conditions : [
+            ['${Height} > 100', 'color("blue")'],
+            ['${Height} > 50', 'color("red")'],
+            ['true', 'color("green")']
+        ]
     };
 
     var jsonExpWithExpression = {
         expression : '${Height}/2',
-        conditions : {
-            '${expression} > 50' : 'color("blue")',
-            '${expression} > 25' : 'color("red")',
-            'true' : 'color("green")'
-        }
+        conditions : [
+            ['${expression} > 50', 'color("blue")'],
+            ['${expression} > 25', 'color("red")'],
+            ['true', 'color("green")']
+        ]
     };
 
     var jsonExpWithMultipleExpression = {
         expression : '${Height}/2',
-        conditions : {
-            '${expression} > 50 && ${expression} < 100' : 'color("blue")',
-            '${expression} > 25 && ${expression} < 26' : 'color("red")',
-            'true' : 'color("green")'
-        }
+        conditions : [
+            ['${expression} > 50 && ${expression} < 100', 'color("blue")'],
+            ['${expression} > 25 && ${expression} < 26', 'color("red")'],
+            ['true', 'color("green")']
+        ]
     };
 
 
     var jsonExpWithUndefinedExpression = {
-        conditions : {
-            '${expression} === undefined' : 'color("blue")',
-            'true' : 'color("green")'
-        }
+        conditions : [
+            ['${expression} === undefined', 'color("blue")'],
+            ['true', 'color("green")']
+        ]
     };
 
 
@@ -60,60 +60,60 @@ defineSuite([
     it('constructs with expression', function() {
         var expression = new ConditionsExpression(jsonExpWithExpression);
         expect(expression._expression).toEqual('${Height}/2');
-        expect(expression._conditions).toEqual({
-            '${expression} > 50' : 'color("blue")',
-            '${expression} > 25' : 'color("red")',
-            'true' : 'color("green")'
-        });
+        expect(expression._conditions).toEqual([
+            ['${expression} > 50', 'color("blue")'],
+            ['${expression} > 25', 'color("red")'],
+            ['true', 'color("green")']
+        ]);
     });
 
     it('evaluates undefined expression', function() {
         var expression = new ConditionsExpression(jsonExpWithExpression);
         expect(expression._expression).toEqual('${Height}/2');
-        expect(expression._conditions).toEqual({
-            '${expression} > 50' : 'color("blue")',
-            '${expression} > 25' : 'color("red")',
-            'true' : 'color("green")'
-        });
+        expect(expression._conditions).toEqual([
+            ['${expression} > 50', 'color("blue")'],
+            ['${expression} > 25', 'color("red")'],
+            ['true', 'color("green")']
+        ]);
     });
 
     it('evaluates conditional', function() {
         var expression = new ConditionsExpression(jsonExp);
-        expect(expression.evaluate(new MockFeature('101'))).toEqual(Color.BLUE);
-        expect(expression.evaluate(new MockFeature('52'))).toEqual(Color.RED);
-        expect(expression.evaluate(new MockFeature('3'))).toEqual(Color.GREEN);
+        expect(expression.evaluate(new MockFeature(101))).toEqual(Color.BLUE);
+        expect(expression.evaluate(new MockFeature(52))).toEqual(Color.RED);
+        expect(expression.evaluate(new MockFeature(3))).toEqual(Color.GREEN);
     });
 
     it('evaluates conditional with multiple expressions', function() {
         var expression = new ConditionsExpression(jsonExpWithMultipleExpression);
-        expect(expression.evaluate(new MockFeature('101'))).toEqual(Color.BLUE);
-        expect(expression.evaluate(new MockFeature('52'))).toEqual(Color.GREEN);
-        expect(expression.evaluate(new MockFeature('3'))).toEqual(Color.GREEN);
+        expect(expression.evaluate(new MockFeature(101))).toEqual(Color.BLUE);
+        expect(expression.evaluate(new MockFeature(52))).toEqual(Color.GREEN);
+        expect(expression.evaluate(new MockFeature(3))).toEqual(Color.GREEN);
     });
 
     it('constructs and evaluates empty conditional', function() {
         var expression = new ConditionsExpression({
-            "conditions" : {}
+            "conditions" : []
         });
-        expect(expression._conditions).toEqual({});
-        expect(expression.evaluate(new MockFeature('101'))).toEqual(undefined);
-        expect(expression.evaluate(new MockFeature('52'))).toEqual(undefined);
-        expect(expression.evaluate(new MockFeature('3'))).toEqual(undefined);
+        expect(expression._conditions).toEqual([]);
+        expect(expression.evaluate(new MockFeature(101))).toEqual(undefined);
+        expect(expression.evaluate(new MockFeature(52))).toEqual(undefined);
+        expect(expression.evaluate(new MockFeature(3))).toEqual(undefined);
     });
 
     it('constructs and evaluates empty', function() {
-        var expression = new ConditionsExpression({});
+        var expression = new ConditionsExpression([]);
         expect(expression._conditions).toEqual(undefined);
-        expect(expression.evaluate(new MockFeature('101'))).toEqual(undefined);
-        expect(expression.evaluate(new MockFeature('52'))).toEqual(undefined);
-        expect(expression.evaluate(new MockFeature('3'))).toEqual(undefined);
+        expect(expression.evaluate(new MockFeature(101))).toEqual(undefined);
+        expect(expression.evaluate(new MockFeature(52))).toEqual(undefined);
+        expect(expression.evaluate(new MockFeature(3))).toEqual(undefined);
     });
 
     it('evaluates conditional with expression', function() {
         var expression = new ConditionsExpression(jsonExpWithExpression);
-        expect(expression.evaluate(new MockFeature('101'))).toEqual(Color.BLUE);
-        expect(expression.evaluate(new MockFeature('52'))).toEqual(Color.RED);
-        expect(expression.evaluate(new MockFeature('3'))).toEqual(Color.GREEN);
+        expect(expression.evaluate(new MockFeature(101))).toEqual(Color.BLUE);
+        expect(expression.evaluate(new MockFeature(52))).toEqual(Color.RED);
+        expect(expression.evaluate(new MockFeature(3))).toEqual(Color.GREEN);
     });
 
     it('evaluates undefined conditional expression', function() {