This essay discusses the manufacture of colors in Venetian and à la façon de Venise glass that was produced from the fifteenth century and codified in print in the seventeenth century. The focus is on “L’Arte Vetraria”, the first printed book on glassmaking, published by the Florentine alchemist Antonio Neri in 1612. In this essay we consider Neri’s recipes for making glass colors in light of the issue of color systematization and standardization. I will show that standardization of glass colors was absent in the seventeenth century prior to the multiplication of color systems in the eighteenth and nineteenth centuries. Neri repeatedly emphasized the importance of judgment by the eye in the production of glass colors.