1923 $1 large size Blue Seal Silver Certificate, Signatures of Speelman & White Grades vf, very fine. FR 237. The term “horse blanket” gets used a lot when talking about large size currency. It is most frequently used to describe this bank note. All large size $1 silver certificates have the same blue seal. There are three signature combinations used with 1923 $1 silver certificates. Portrait of George Washington at center.