Robert Indiana kept a series of illustrated journals during the late 1950s and 1960s, in which he discusses the development of his work as well as his daily life on Coenties Slip.

In his journal entry for July 2, 1962, Indiana records that he woke up early after having spent the previous day in the country, and "had much light [to] work by and accomplished a great deal." The entry includes a sketch of the painting Coenties Slip, below which the artist comments "reinforce [the] red [letters] of ring by a shadow of black. Paint 1st coat on bot[tom] row: yellow." 

The entry also includes sketches of the sculptures Gem and 4 (Four). Discussing Gem Indiana writes that he turned it into the "black construction" by painting the front of the work lamp black, and that he took out the red star as well as the bottom indenture. For Four he records that he reinstated its numerals to gesso white in preparation for other alterations.