How can a man differentiate between a virgin and a non-virgin, and what are the implications if the agreement stipulated in the marriage contract is not fulfilled?

A virgin is she who has not been deflowered, and a non-virgin (thayyib) is she who has been deflowered and whose virginity has been lost. Virginity may be lost by means other than intercourse. If a man stipulates his wife to be a virgin, and she turns out to be a non-virgin due to intercourse, he has the option [to annul the marriage]. If he stipulates her to be a non-virgin and she turns out to be a virgin, he has the option [to annul] if he had a valid reason for his stipulation. However, if she is a non-virgin due to means other than intercourse, he has no option. The option [to annul] is established provided the husband had no prior knowledge [of her condition] or did not derive pleasure from her after coming to know [of her condition].