The ammonite is from Madagascar (I'm afraid I don't have the specific name), however according to the supplier it is from the Late Jurassic . The photos are not particularly informative - but I do think they're quite pretty.
The lighting was positioned differently for the two photos.
The second photo (stackX9) shows a chamber where the calcite crystals growth has failed to completely fill the available space. In my experience this is quite rare. The crystal opening is approximately 1.5 mm measured across the longest point. In both photos the misty areas actually are indistinct and smokey in reality and hint at underlying structures (mainly the folded septa) seen through the variously tinted calcite. As a separate exercise, I did try focusing down through the calcite but the results were disappointing (even to the eye).
Bruce

