Why the necklace was kept in a box with such a label.

Maybe it is as simple as when fleeing France, Empress Eugenie just grabbed the nearest empty box and threw in some of her jewels and escaped, it is quite an interesting mystery.

I was a bit surprised at how relatively low the estimate for this necklace is, I think Empress Eugenie and Napoleon III aren't maybe as iconic historical figures as Napoleon and Josephine were. I also suspect the quality of the stones are not as good as many of the crown jewels that were auctioned.