This six-step series by James Ronca was made in about 1850-90 to illustrate the preparation of a shell cameo portrait from its earliest state, the shell itself, with a section for the cameo removed, to the finished portrait of John Everett Millais, the pre- Raphaelite painter. Intermediate stages demonstrate how the carver cut a rough blank and sketched on the shell a pencil outline of the portrait. Outer layers of the shell were then partially stripped away and the profile cleared right to the ground (the bottom or inside layer of the shell). In the final state, fine details such as hair are silhouetted against the dark polished ground, while portions of the upper layer are retained to give colour and relief to the head. As well as being clearly instructive, the series is a virtuoso example of nineteenth-century shell cameo carving and shows how the more experienced carvers in the medium could produce work of a quality rivalling that of the more costly and prestigious hard-stone cameos.

While a gemstone cameo was far harder to cut than a shell cameo, the basic principle was the same. The engraver, using chisels, drills and abrasives, worked inwards from the surface of the blank, retaining or removing material until the subject slowly emerged. Layers of contrasting colours occurring naturally within the chosen stone or shell would be skilfully used to create the image.

James Ronca (1826-after 1908), a carver of cameos in hard stones and shell, who had for thirty years produced the cameo portraits of Queen Victoria and Prince Albert that were mounted in the Royal Victorian Order, the Queen's personal award.