diff --git a/FeatureRenderer.pyt b/FeatureRenderer.pyt
index 21ac278..f8980fb 100644
--- a/FeatureRenderer.pyt
+++ b/FeatureRenderer.pyt
@@ -782,5 +782,7 @@ def get_symbol_color(color_string):
         return {
             "CMYK": [100, 100, 100, 0, 100],
         }
+    elif color_string == "GRA":
+        return {"CMYK": [10, 10, 10, 21, 100]}
     else:
         raise ValueError(f"Execution aborted: unknown color code {color_string}")