Quoting from [santahw050]:
Two ways:
1. whether the buyer is willing to provide you with his/her full company information?
2. whether the buyer is willing to provide a bank comfort letter (BCL) to show he/her has money for the purchase?
There are many other ways, but these are quick ways.
I think that it depends what level of discussion you are up to.
If the customer is making initial enquiries and you push the above on to them then you run the chance of losing the customer.
Of course if discussions have been had and the customer is ready to place an order then that is the stage that the customer would welcome your due dilligence efforts.