When d'Urberville got back to the tent he sat down
astride on a chair reflecting, with a pleased gleam in
his face.  Then he broke into a loud laugh.
"Well, I'm damned!  What a funny thing!  Ha-ha-ha!
And what a crumby girl!"

"What's her trump card?  Her d'Urberville blood, you
mean?"
"No, stupid; her face--as 'twas mine."

To Tess's horror the dark queen began stripping off the
bodice of her gown--which for the added reason of its
ridiculed condition she was only too glad to be free
of--till she had bared her plump neck, shoulders, and
arms to the moonshine, under which they looked as
luminous and beautiful as some Praxitelean creation, in
their possession of the faultless rotundities of a
lusty country girl.

"Tess, why do you always dislike my kissing you?"
"I suppose--because I don't love you."
...
As Tess's own people down in those retreats are never
tired of saying among each other in their fatalistic
way: "It was to be." There lay the pity of it.  An
immeasurable social chasm was to divide our heroine's
personality thereafter from that previous self of hers
who stepped from her mother's door to try her fortune
at Trantridge poultry-farm.

Here Hardy reveals Alec's true malice in his use of Tess as nothing more than a way to pass the time, and proud of his accomplishment, foreshadowing his future treatment of Tess later in the novel.

This passage is ironic in that what is her trump card may well be the reason for her downfall.

Here Hardy uses classic allusion to refer to the famous Greek sculptor in relation to the girl’s figure in the moonlight.

Having expressed her dislike for Alec, it is ironic later in the passage that Alec takes it upon himself to force his love upon her, and become the foil through which her innocence was to be penetrated, destroying any chance for happiness down the line.