décollété
Décollété (adj, n) refers to the low neckline on a woman's dress or top.
The décollété blouse displayed her ample cleavage.
staged décollété
This is the deliberate display of significant cleavage; whether through the choise of a daring low-cut dress or blouse, or positioning in order to emphasize the breasts.
Judy provided some staged décollété, much to the pleasure of Mike, Bob, and Joshua.