A group of late 18th/early 19th century gold and enamel jewellery

A group of late 18th/early 19th century gold and enamel jewellery
Comprising: an oval blue enamel pendant with applied rose-cut diamond monogram; a heart-shaped blue enamel pendant with central applied rose cut diamond legend ja toi within rose-cut diamond border to a diamond crown surmount; a lozenge-shaped blue enamel brooch with central pear-cut diamond and old mine brilliant-cut diamond border; a navette shaped blue enamel brooch with rose-cut diamond three stone centre, diamond points and border; and a gold blue enamel and seed pearl ring modelled as a miniature bracelet