Cameo Appearancefeatured news
A cameo is defined as a gemstone that has been carved in relief with a picture of a scene, figure or face. One of the most widely-used is a portrait of a face in profile. KATHERINE KOVACS reports.
Gemstones that have two or more layers of colour are favoured for carving into cameos, as the contrast of a lighter layer against a darker colour makes the detail of the carving stand out. Chalcedony (many varieties of which are simply called agate), with its multiple layers of colour has been a popular choice since ancient times.
Varieties of shell (the helmet and the pink conch) have also been used for cameos since the 15th or 16th century, and this is probably the most popular material for cameo carving today.
When buying cameos, jewellers should look out for plastic that may be used to imitate shell cameos, and this can be detected with 10x loupe examination or the potentially destructive “hot point” test.
Natural shell cameos can be quite thin, making the back susceptible to cracking. If this happens, the carved part may be cut-out and glued onto new backing material – the term for this is “doublet”. Opal and other gems are sometimes also used to make cameo doublets with backing materials such as onyx or plastic.
The birthplace of the cameo is said to be Alexandria where its founder, Alexander the Great, reputedly commissioned the first cameo in approximately the third century BC. The rulers of this time believed themselves descended from the gods. As such, artists of that first cameo didn’t portray Alexander realistically, but as their impression of the god, Zeus.
While carving into stone wasn’t new, the introduction of sardonyx from India enabled the artist to carve away a lighter top layer of the gemstone to create a picture against a darker bottom layer.
The cameo continued to gain popularity through the Hellenic and Roman times with its artistic zenith said to be around the first century BC. Cameos were worn in rings, pendants, bracelets and clothing ornaments and continued to commonly represent myths or artistic representations of the gods.
With the arrival of the early, austere Christians, the cameo declined in popularity before being revived in the Renaissance, where artists sought to copy the early ancient gem carvings. The Victorian era also saw a revival of classical themes. Today, some cutters seek to replicate the ancients by choosing a Grecian or Roman hairstyle for an anonymous profile.
The hand carving of cameos is a highly skilled art. For gemstones like chalcedony, the process involves sketching a design onto the stone with a diamond stylus.
The background is then cut back using an increasingly finer and finer number of drill points as the image goes from a roughly-formed shape to an image of greater detail. Because they are softer, the hand carving of shells requires less abrasive instruments, such as hand gravers and dental drills.
Polishing should be performed with extreme caution as the process has the potential to destroy fine detail. As the cameo nears final stages, carving and polishing may be done alternatively. Hand carving a gemstone or shell into a cameo is understandably a time consuming, and therefore costly, process, hence the now widespread use of an ultrasonic cutting machine for cameo mass production. A metal casting is made of the image to be used, and loaded into the machine.
This machine vibrates at thousands of times per second while an abrasive agent, suspended in liquid, hits the stone and chips-off microscopic flakes.
Ultrasonically-carved cameos can be differentiated from handcut ones as the ultrasonic method can’t “undercut” or carve out the background to leave the image in relief. Some manufacturers try for a balance between the two and choose to produce cameos with the ultrasonic machine and finish the piece with hand-carving.
Hand-carved and ultrasonically produced cameos may be further distinguished using a 10x hand lens. The cameo produced by the ultrasonic will have a slightly pitted surface, and may feel slightly rough to the touch; a hand-carved piece will feel smooth.
Factors affecting the value of antique cameos include the material used, provenance, age, condition, subject matter, depth and detail of the carving.
For more modern pieces, the most important factor affecting value is the quality and detail of the carving; however, a cameo made by ultrasonic will generally be worth less than a well-executed hand-carved piece.
Katherine Kovacs BA, FGAA is a gemmologist with over 15 years experience. She is a wholesaler of natural gems and fancy coloured diamonds, and a member of the GAA.