A proprietary mix of molten pig iron, steel and other ingredients are poured into a mold made of sand. Since sand melts at a higher temperature than iron, the mold holds its shape. Once the cast iron pan or pot has cooled, the sand mold is broken, leaving behind a brand new piece of cast iron cookware.
A well-seasoned cast-iron skillet is black because cooking oil has polymerized on the surface with the seasoning and the skillet's daily use. If you remove the seasoning, the color of the cookware will usually change to metallic gray. Cookware, you see, is made out of two types of metals.
The main difference between iron cookware and cast iron cookware is that it is composed of smelting iron with metal alloys. In contrast, the former is composed only of iron and contains no alloys. Iron cookware is crafted of pure iron, which makes it very long-lasting.
A real cast iron skillet should be all one piece - no seams and no screwed on handles. Check the pan's surface. It should look the same as the rest of the pan with no other materials. A raw cast iron pan will have a dull black/dark grey color and be slightly rough to the touch.