I don't get it...I mean, currency is something that is either made of metal or some substance that is very hard to get in the local area...such as shells when you are in the middle of the country and 1000 miles from the ocean.
Transporting shells in land and having them traded inland begins a form of currency because they are hard to get; come a long way; and are deemed worth 2 pigs and a duck for a really nice shell. For the new owner to part with it now means 2 pigs and 2 ducks...and sea shells become a form of currency far inland away from the ocean.
For the material the discs are made from, anyone can get that; anyone can carve images upon it; anyone can make a disc from it. That would mean 'currency' is made on the spot in about an hour and is suddenly worth a house? A pig? 2 ducks? What would something be worth when any and everyone can make it in an hour?
I think you have a really good collection of game tiles that, if really really old, might be the precursor to Mahjong AND chess combined.
For larger tiles, a larger board is used with larger rods upon which the tiles are placed so a gathering of people can watch the game. For larger, rectangular tiles with no holes, now you are getting towards the concept of Mahjong.
If you think these are from an old tomb, then you have to accept that the larger tiles - both round and rectangular, no matter if rock or glass - were owned by an official or wealthy person and used upon a large board with many people watching the game. The small round tiles are the portable game...taken on travels or played at the local cafe where old men gather and chew the fat for half the day.
Now then...where were these tiles found? That starts to undo the puzzle...the material they are made from: where is it found? The glass ones: where was glass being made? The style of the characters and what they actually say: which dialect is it and which province used it? And finally, where did Mahjong begin: there will be one region of origin where Mahjong began and either that region or a region right next to it will be where these tiles come from.
I guess this is a challenge to have some fun with. I might just have some fun David, and see what things I can put together based upon actual evidence that could support these being game tiles. Sure, they very well might not be, but at least we may know more about them than just speculations, right? I mean...you don't write a book on fiction, do you? Or it's fiction, not fact. You wrote a book on fact, yes? Research and all that?
I bet you might just have another book to write about a game lost to history...and a little history on the game that ended up in your possession.