diff --git a/res-common/values/colors.xml b/res-common/values/colors.xml
index 968e5e6..8700256 100644
--- a/res-common/values/colors.xml
+++ b/res-common/values/colors.xml
@@ -55,22 +55,57 @@
     <color name="textColorIconOverlay">#fff</color>
     <color name="textColorIconOverlayShadow">#000</color>
 
-    <!-- Make sure to also update LetterTileProvider#NUM_OF_TILE_COLORS when adding or removing
-    colors -->
+    <!-- Background colors for LetterTileDrawables. This set of colors is a subset of
+        https://spec.googleplex.com/quantumpalette#extended which passes Google Accessibility
+        Requirements for the color in question on white with >= 3.0 contrast. We used
+        http://leaverou.github.io/contrast-ratio/#white-on-%23db4437 to double-check the contrast.
+
+        These colors are also used by MaterialColorMapUtils to generate primary activity colors.
+    -->
     <array name="letter_tile_colors">
-        <item>#f2b31b</item>
-        <item>#f8971c</item>
-        <item>#f0592b</item>
-        <item>#db4436</item>
-        <item>#d5197e</item>
-        <item>#8f3e97</item>
-        <item>#65499d</item>
-        <item>#547dbe</item>
-        <item>#38a4dc</item>
-        <item>#0b9c57</item>
-        <item>#8bc248</item>
-        <item>#666666</item>
+        <item>#DB4437</item>
+        <item>#E91E63</item>
+        <item>#9C27B0</item>
+        <item>#673AB7</item>
+        <item>#3F51B5</item>
+        <item>#4285F4</item>
+        <item>#039BE5</item>
+        <item>#0097A7</item>
+        <item>#009688</item>
+        <item>#0F9D58</item>
+        <item>#689F38</item>
+        <item>#EF6C00</item>
+        <item>#FF5722</item>
+        <item>#757575</item>
     </array>
+
+    <!-- Darker versions of letter_tile_colors, two shades darker. These colors are used
+        for settings secondary activity colors. -->
+    <array name="letter_tile_colors_dark">
+        <item>#C53929</item>
+        <item>#C2185B</item>
+        <item>#7B1FA2</item>
+        <item>#512DA8</item>
+        <item>#303F9F</item>
+        <item>#3367D6</item>
+        <item>#0277BD</item>
+        <item>#006064</item>
+        <item>#00796B</item>
+        <item>#0B8043</item>
+        <item>#33691E</item>
+        <item>#E65100</item>
+        <item>#E64A19</item>
+        <item>#424242</item>
+    </array>
+
+    <!-- The default color used for tinting photos when no color can be extracted via Palette,
+            this is Blue Grey 500 -->
+    <color name="quickcontact_default_photo_tint_color">#607D8B</color>
+    <!-- The default secondary color when no color can be extracted via Palette,
+            this is Blue Grey 700 -->
+    <color name="quickcontact_default_photo_tint_color_dark">#455A64</color>
+
+
     <color name="letter_tile_default_color">#cccccc</color>
 
     <color name="letter_tile_font_color">#ffffff</color>