6 F/VFOG singles of the 1/2d - 6d green - dull & bright purple Seated Britannia from the 1921-1922 Seated Britannia Keyplates Issue, script ca wmk, includes 7 shades of 2.5d bright blue.
Gibbons values these at £12.3, so we estimate them at $12. The stamps offered here grade between 70 and 80 as follows:
