@@ -1,4 +1,12 @@
+-- compatibility tables
+-- this file is used to hold information that would normally
+-- be tagged in the _sorcery or _proto fields of an item's
+-- definition, but cannot be placed there because the item
+-- is outside the control of the author and its module does
+-- not cooperate with sorcery. it is used by itemclass.lua
+-- to seamlessly locate the material properties and
+-- capabilities of an item.
 local grain = {
 	hardness = 1;
 	value = 1;
 	powder = 'farming:flour';
@@ -21,6 +29,20 @@
 		['default:mese'] = {
 			power = 0.25;
 			mode = 'produce';
 		};
+	};
+	gems = {
+		['default:mese_crystal'] = {
+			id = 'mese', gem = true;
+			value = 9, raw = true;
+		};
+		['default:mese_crystal_fragment'] = {
+			id = 'mese', gem = true;
+			value = 1, raw = true;
+		};
+		['default:diamond'] = {
+			id = 'diamond', gem = true;
+			value = 9, raw = true;
+		};
 	};
 }