Not quite sure what you mean by laminated. Do you mean it is glued together? From what I know, the beads that come from Idar Oberstein, and these do look like they do, are made from a single piece of stone. Or do you mean layered?

Here are some examples from museums in Idar Oberstein.

#1. First hand, you can feel a gap or a ridge with your finger nails.

#2. By visually following the grain in the white agate, you can see where it ends... Whereas, the black agate appears to be grainless.

#3. In person, you could determine that each white band is exactly the same width and perfectly centered in every bead.

Just Fred