Value of $50 Silver Certificate

$50 Silver Certificates

Fifty dollar silver certificates were printed for 1878, 1880, and 1891.  They feature a portrait of Edward Everett on the right hand side of each bill.  The 1891 example can have a red seal or blue seal.  The earlier examples are much more difficult to locate.  If you have any year available, please let me know.  I would be a serious buyer.