Learn the correct pick-up :)))

The jewelry store guy comes accompanied by a very beautiful girl.
 Together they choose a big diamond for 50,000 euros.
A man pulls out a checkbook and writes a check for the appropriate amount.
 Seller looks at him incredulously.
A man says:
 - I understand that I am not your regular customer and you're not sure that I have the account such amount, right?
 - No, you just ... when it comes to such a sum ... we usually ...
 - Do not worry. Let's do so.
Today is Friday, time for 17 hours, and all banks are closed, so even if a diamond is still you.
 And on Monday, when the banks open, you check the check and send the diamond to my girlfriend.
 Seller agrees.
But on Monday, he calls it a man and says:
 - I'm sorry, but I called your bank and they told me that you have on the account of such amount no.
 - All right, a diamond can once again put up for sale, and a check to break, I have already ...