Aigrette

a plume or tuft of feathers, especially the back plume of any of various herons, arranged as a head ornament.
a jeweled ornament depicting or suggesting this, usually worn in the hair or on a hat.
Historical Examples

She stretched herself, shaking back her head, while the diamond points of her aigrette danced and glittered.
The Far Horizon Lucas Malet

The Man glanced at the aigrette, smiled discreetly, and said nothing.
The Secret Trails Charles G. D. Roberts

Her daughter, Lady Dering, came also arrayed in a queenly dress of amber silk with an aigrette of feathers in her hair.
The Ivory Gate, a new edition Walter Besant

The law is in effect; and the aigrette business is dead in this state.
Our Vanishing Wild Life William T. Hornaday

She had shaken hands with him and received her costume which was an aigrette and a peacock-feather fan.
Tutors’ Lane Wilmarth Lewis

From the aigrette in her hair to the paste buckle on her shoe she was mondaine.
Hilda Sarah Jeanette Duncan

Miss Pritchett flushed and tossed her head till the aigrette in her smart little bonnet shook like a leaf.
A Lost Cause Cyril Arthur Edward Ranger Gull

If I am correctly informed, the London feather trade admits that it requires six egrets to yield one “ounce” of aigrette plumes.
Our Vanishing Wild Life William T. Hornaday

A black satin toque, with aigrette of diamonds, contrasted well with the white wig.
The Evolution of Fashion Florence Mary Gardiner

He published a succession of pages showing the frightful cost at which the aigrette was secured.
The Americanization of Edward Bok Edward William Bok

noun
a long plume worn on hats or as a headdress, esp one of long egret feathers
an ornament or piece of jewellery in imitation of a plume of feathers