Question

how many diamond cards are there in an ordinary pack of 52 cards

Answer 1

13

Answer 2

The deck of 52 French playing cards is the most common deck of playing cards used today. It includes thirteen ranks of each of the four French suits, clubs (♣), diamonds (♦), hearts (♥) and spades (♠), with reversible "court" or face cards.

Source: http://en.wikipedia.org/wiki/Standard_52-card_deck