Four-Color Agate Cameo

Glyptic art is an ancient passion. Carving a cameo is always an especially new and fascinating adventure. The art of engraving pictures into gemstones has a thousand-year-old history. The working methods have hardly changed since the art's earliest beginnings. Nowadays, one can still choose to work with a fixed axis, but the modern era has also given us the option of using a flexible-shaft machine.

Use diamond burrs and water to carve the stone. I keep a small bowl of water near my workplace and repeatedly dip my fingertip into the bowl and apply drops of water to keep the stone moist. An artist's paintbrush is convenient for brushing away the powder produced during the grinding and for checking the progress of the cut. Dipped in water and brushed across the stone, the paintbrush cleanses the surface of the gem. Keep the stone moist while you work. Otherwise, the material is liable to overheat from the friction produced by the burr. Overheating can damage both the gem and the burr.

Editor's note: To read about this lapidary artist, see "Outside the Tradition," page 38 of January 1999 Lapidary Journal.

STEP 1.
Draw a colored sketch of the cameo in which the dimensions exactly correspond to the size of the stone. This sketch helps determine exactly which layers must be ground away and which must be allowed to remain. Afterwards, make a full-size copy of the sketch. I leave the original intact to serve as a model and cut apart the copy in the course of my work on the stone. The sketches, however, only determine the location of exterior contours and outlines. The finer details of the cameo will take shape while you work.

I repeatedly grind away my reference lines immediately after I've drawn them. The sketch serves as a reminder for my visual memory.

STEP 2.
To determine how far each particular layer needs to be ground away, use scissors to cut the corresponding portions of the design from the paper copy, beginning with the part of the design that corresponds to the uppermost black layer, which must remain intact. This also includes the portion that will later become the thin brown layer atop the angel's wings. Use double-faced adhesive tape to precisely affix the paper pattern upon the stone, then brush on a thin layer of colorless lacquer. The lacquer shields the paper from the water and the stone dust, thereby preventing it from disintegrating too soon.

STEP 3.
Grind away the uncovered portions of the black layer until you reach the white substrate. A large, ball-shaped burr is well suited for this task, although one must take care to avoid cutting furrows in the white substrate. Using a flat burr to remove the last remnants of the black layer minimizes the danger of furrowing. The same burr is also used to grind away the dark layer above the angel's wings until nothing but a very thin brown layer remains.

STEP 4.
Remove the paper mask and cut a template from the paper pattern that corresponds to the white areas (the head and wings). Glue the template to the stone and apply a coat of lacquer. Now grind away the layer of white stone from all parts of the design, which will eventually form the background. The angel's head and wings should remain as a raised outline. When carving the background areas, one must be careful not to grind away too much white stone. Only remove white until a lovely blue tone appears. A conical burr is the best tool for carving the sharp edges that separate the blue background from the white head and wings. You can remove the paper mask now to begin working on the fine details.

STEP 5.
Use a pencil to draw the features of the angel's face on the white stone. Proper proportions for the eyes, nose, mouth, and hairline are particularly important. The tip of the nose is the highest point in the relief; the rest of the face lies deeper within the stone. Use a small, ball-shaped burr (2mm in diameter) to grind the concavities for the root and sides of the nose, corners of the mouth, and the area around the eyes.

Use a cylindrical burr to carve the hairline and the outline of the face, and to separate the neck from the hair. Now remove enough stone from the hair down towards to the neck so that this part acquires a light blue shimmer, which helps distinguish it from the face and neck.

Use various large, ball-shaped burrs to shape the face, always beginning from the nose. The cheekbones must be left in high relief, and be careful not to grind away too much stone from the mouth and lips. I use a flat, sharp-edged burr to slightly undercut the black edges so that I can readily grind away the surface of the face all the way to the black edge. A pointed burr is helpful for working on small corners.

STEP 6. Once the face is finished, begin working on the gradations of color in the wings using a large, ball-shaped burr. Leave the brown layer as is, and grind away just enough of the white layer on the inner edge of the wings and towards the top so that a blue shimmer appears.

STEP 7.
Now draw the individual feathers with a pencil and use a cylindrical burr to carve their outlines to a depth of approx. 1mm. I use a flat burr to grind away the waste stone above those feathers, which need to lie at lower depths, carefully shaping them to the edge of their adjacent feathers. This procedure creates the impression of layering. A ball-shaped burr is used to slightly hollow out the inside of some feathers. The blue tone can be made somewhat darker at this stage. The outlines of the feathers are engraved into the brown layer, deep enough to allow the underlying white to shine through.

STEP 8.
Smooth the blue background and precisely define the edges where the background abuts the head and wings. A lenticular burr helps to slightly undercut the head and wings so that a sharp edge is created. With a flat burr, carefully and gradually remove material from the background until you have created an attractive gradation from dark blue to pale blue. Use a ball-shaped burr to smooth the face.

STEP 9.
Now finish the wings. A small cylindrical burr carves details into individual feathers. Use a ball-shaped burr to smooth and polish the rest, round the edges of the black layer, and remove any raised irregularities.

STEP 10.
Give the matte stone a shinier appearance with a rubber corundum eraser, available from goldsmith suppliers. Very little stone is actually removed, but the corundum rounds the sharp edges somewhat, so use extreme caution when polishing the face. The final polishing is done with a brush and polishing compound, such as goldsmith's polishing paste. A high-gloss finish is not possible, but this final polishing is especially effective on the blue background, which seems to glow more brightly afterwards. Here again, always keep the stone moist.

Good luck, good fun, and good success!