In addition to printing philatelic products, FNMT-RCM joins forces with Correos (the Spanish Post Office) in the issuance of combined series of collector coins and stamps.

In 2014, the artist's proof of the block sheet commemorating the Fourth Centenary of El Greco's death was issued. A detail from the painting "View and plan of Toledo" is framed within the stamp.

The proof shows the work titled View and plan of Toledo, preserved at the El Greco Museum (Toledo). The painting offers a multiple perspective of the city, along with a number of allegories and a young man showing a plan, all depicted in El Greco's characteristic brush strokes. A detail from the painting is framed within the stamp, where St. Ildefonsus is seen to be receiving the chasuble from the Virgin.

The artist's proof and the 24-carat gold stamp covering a reproduction of the 999 thousandths silver stamp come with a Certificate of Authenticity.