Antique Mid 18th century portrait miniature framed brooch

An antique mid 18th century Portrait miniature in a Cannetille frame brooch - an oval head and shoulders portrait of a Georgian lady wearing a double ruffle choker and cap style hat in a lilac gown with lace trim and with a sprig of flowers at the bust against a striking blue graduated background - the brooch of heavy gauge 15k gold with a rolled edge within a border of alternating flowers and coil and ball finials - unsigned but typical of either of the two Lens brothers Andrew Benjamin Lens and Peter Lens - total weight 23grms - overall dimensions 49 x 42mm - c.1750 England