was carved from a four-layered sardonyx. It is a fragment of a larger portrait of the Roman emperor-Augustus. "The head of Flora Cameo" – Benedetto Pistrucci. 1812 AD. In this cameo the top red-brown layer has been carved into roses. The face is carved from the white layer. The collector Richard Payne Knight purchased the Flora cameo from an Italian dealer, believing it to be Roman. The Italian carver Pistrucci claimed to have carved it himself. Payne challenged Pistrucci to carve a copy to prove his claim. The ensuing publicity earned Pistrucci several commissions. Schaffhausen onyx – Roman, Augustan-era, depicting Pax Augusta or Felicitas Modern cameos Many modern cameos are carved into layered agates. The layers are dyed to create strong color contrasts. The most usual colors used for two-layer stones are white on black, white on blue, and white on red-brown. Three-layer stones are sometimes made. The colors are usually black on white on black. The layers are translucent; this allows the artist to create shading effects by removing material to allow the background layer to show through. This way a very realistic, lifelike quality to a figure can be achieved. For example, thinning the top black layer on a three-layer stone changes its color to shades of brown. Removing material from the white layer creates shades of blue or grey, depending on the color of the base. Ultrasonic machine carved cameos The majority of modern agate cameos are carved with the aid of the Ultrasonic Mill. This is a process where multiple copies of a master design can be produced very quickly by pressing a master die onto the agate cameo blank. A film of diamond slurry is used to aid cutting and the die vibrates ultrasonically in a vertical motion. The master is often hand carved by a skilled cameo artist. The result is a cameo that has a satin surface texture described as "freshly fallen snow" (FFS) by Anna Miller. This texture and the lack of any undercutting are used by appraisers as markers to prove that the cameo is machine-made. Hand-worked portrait cameos These cameos are carved by hand, usually working from photographs of the subject. The fact that there is usually only one copy made means that the tooling costs involved rule out the ultrasonic carving process. There are very few people working in this field, as this is one of the hardest challenges