Blue corundum.

Blue corundum, to be precise. Blue corundum.

Blue corundum, to be precise.

Blue corundum. Well, it's very pretty.

It's a corundum in the trigonal crystal system and the hexagonal scalenohedral class.

The list covers certain mineral products (marble, granite porphyry, natural magnesium carbonate), ores (iron, manganese, copper, cobalt, lead, zinc, tin, tungsten), mineral fuels (oils, pitch, petroleum oils and gas), chemical products (artificial corundum, manganese oxides), precious stones (pearl) and copper and articles.