I lost my 100k diamond I didn't know what happen, how to check or refund my diamond?

Mine disappeared too. No customer support. this doesn't look good for the game. its 99.00 for 20000 diamonds. i got ripped off by the game.

If you haven't already done so check your items menu to see if you have been given the diamonds as stored items to convert into the diamonds.

If not then you would need to contact the in game support as they would need to check any purchases and make any refunds.