These are interesting items, but they are most likely not seals.

A seal is normally carved intaglio (having a recessed reverse design), so that they can serve the function of being used as a seal, to present a relief image.

The objects you show are cameo-carved—that is, carved in low relief (though heavily outlined). This is the reverse of intaglio work, but when used as a seal would produce an intaglio image. I don't think this ever happened with real seals.

What else can you tell us about these things?

Jamey