A puzzle!

These little dice are part of a box for writing and games that my grandparents brought back from India some hundred years ago, where my grandfather had been a Methodist missionary. The dice are very tiny - about 3.5 mm cubes - and there's something wrong about them. Can you tell what?

The box is a beautiful mosaic of tiny bits of - I image - ivory. It's not in perfect condition, as you can tell. Bits of the mosaic are missing. The dice are sitting on a solitaire board, or for a game called Fox and Geese, I believe. Next to it is a chess/draughts board. Inside, there's a backgammon board, and compartments for all the little pieces and pens and paper, together with a velvet writing surface.

So, what's up with those dice?