Nice to be able to share information !
'the pawn, called 'bia,' is traditionally a cowrie (or cowry) shell.
Are cowrie shells still used today in Thailand' is correct... Bia was
the
small changes like coins at that time, as compared to 'gold nuggets'
that were like currency notes... But I do not know what they used for
other big pieces then...
Nowadays, everybody use plastic sets... and may be soda bottles' caps in
place of lost pawns... cowrie shells, as a form of money before coins,
are
now rare collectible items of much values... even the boards are now
plastic or 'imitation wood made from pressed-papers' although some
people still have hand-carved wood sets and boards (also very rare and
collectible-items because nobody makes them anymore > no buyers)