Georgiana, Duchess of Devonshire, was considered one of the beauties of her time. But it wasn't so much her looks, as her personality and manners, that charmed people. Here's how her contemporary Wraxall described her:
"The personal charms of the Duchess of Devonshire constituted her smallest pretensions to universal admiration; nor did her beauty consist, like that of the Gunnings, in regularity of features, and faultless formation of limbs and shape; it lay in the amenity and graces of her deportment, in her irresistible manners, and the seduction of her society. Her hair was not without a tinge of red; and her face, though pleasing, yet, had it not been illuminated by her mind, might have been considered an ordinary countenance."
This made her beauty and likeness difficult to capture on canvas. It is rumoured that, even the famous painter Gainsborough, while painting a portrait of the Duchess "drew his wet pencil across a mouth all thought exquisitely lovely, saying, 'Her Grace is too hard for me.'"
However, as the years passed, her beauty, like Walpole remarked, started to fade: "The Duchess of Devonshire, the empress of fashion, is no beauty at all. She was a very fine woman, with all the freshness of youth and health, but verges fast to a coarseness.". This despite a petition to time not to make Georgiana's beauty fade, made by a certain "Peter Pindar" (Dr. Wolcot):
"Hurt not the form that all admire.
Oh, never with white hairs her temple sprinkle!
Oh, sacred be her cheek, her lip, her bloom!
And do not, in a lovely dimple's room,
Place a hard mortifying wrinkle.
"Know shouldst thou bid the beauteous duchess fade,
Thou, therefore, must thy own delights invade;
And know, 't will be a long, long while
Before thou givest her equal to our isle.
Then do not with this sweet chef-d'oeuvre part,
But keep to show the triumph of thy art."
Some Old Time Beauties by Thomson Willing