How to see if cast iron cookware is enameled?
We're going to do all of our analysis on the back side, so we don't mess up any cooking surface:


if it's rusted : not enameled (or possibly damaged enamel)
if it's greasy, clean w/ hot soapy water and a scrubbing pad, just in the middle of the pan.
if it's any color other than black, brown, bare metal or orange-brown : enameled
look for a model number, then look it up online


... that should get you though 99% 90%  of the cases ...  if that still doesn't help:


run your fingers over the cleaned surface
if it's rough : not enameled (or someone polished the surface ... which is rare, but not impossible; also beware of more recent 'satin enamel', but that's typically an interior treatment)
if there's signs of crazing (tiny cracks all over the place; not sure how obvious it'd be w/ black enamel) : enameled


If you're still not sure after that, I guess post a picture, close up of the cleaned back side, with good lighting.