The tradition of altering the colour of the agate with dyes, is an ancient one. There are many examples of translucent engraved gems being mounted above shellac to alter the colour of the stone. Here it would appear that a thin layer of pigment has been trapped between two layers of stone to alter the background colour of the gem.
A similar style of depiction of Alexander the Great as the cameo completed by Giovanni Pichler. Hecker completed his apprenticeship at the studio of Giovanni Pichler and received his first orders from Pichler, such as a portrait of Pope Clement XIV, presumably commissioned in 1784. Among his most famous patrons was the poet Goethe, who visited Hecker’s studio during his visit to Rome.