1770s portraits (from top to bottom) -

1771 Hester, Countess of Sussex, and Her Daughter, Lady Barbara Yelverton by Thomas Gainsborough (Toledo Museum of Art - Toledo, Ohio, USA). From Wikimedia.

1776 Charlotte Bettesworth (c.1755–1841), Mrs John Sargent by George Romney (Sudley House - Aigburth, Liverpool, Merseyside, UK). From bbc.co (now artuk.org).

1777 Margherita Sparapani Gentili Boccapadule by Laurent Pécheux (location ?). From tumblr.com/history-of-fashion/703331047465713664/1777-laurent-pécheux-margherita-sparapani; sized to fit screen 1010X1400 @72 464kj.

1777-1778 The Honourable Miss Monckton by Sir Joshua Reynolds (Tate Collection - London UK). From their Web site; removed spots throughout image with Photoshop.

Some 1790s (from top to bottom) -

1790s Lady by Rose-Adélaïde Ducreux (private collection). From tumblr.com/historical-fashion-devotee 1048X1600 @72 322kj.

1791 The Singer Rose Renaut by Antoine Vestier (Phoenix Museum - Phoenix, Arizona, USA). From tumblr.com/sims4rococo76; enlarged to screen 1027X1300 @72 357kj.

ca. 1795 or 1797 Alexandra Grigorievna Kozitskaya by Élisabeth-Louise Vigée-Lebrun (auctioned by Tajan). From tumblr.com/antiquelaceartist; fixed spots & flaws w Pshop 1263X1498 @72 1.1Mj.

1790s Woman (Miss Frances Winnicobe?) (Hermitage). From tumblr.com/artthatgivesmefeelings/690087093119188992/john-opie-cornish-1761-1807-portrait-of-a; fixed cracks, flaws, & spots w Pshop 1561X1999.