If you are reading this article, it is a virtual certainty that you own a cameo or two, or 300, that you bought on line, with only photographs and the seller’s assertions on which to base your decision whether to buy or not. This article offers tips on how to recognize different cameo materials and how to distinguish those that look very similar one from the other. Because there appears to be a strong need for this information, the article is being put up as a work in progress.
Even professional jewelers sometimes make mistakes concerning the material in which a cameo is carved. Listings identifying carnelian/sardonyx hardstone cameos as shell (example), and vice versa, are seen regularly. In some cases it is very difficult to be certain whether a piece is coral or shell, carnelian or glass, even when you examine it directly, loupe to eye. Judging from photos can be even trickier. There are no absolute rules for how to distinguish similar looking materials one from the other. However, as long as the seller has provided pictures that are clear and show the piece from many angles, it is possible in most cases to tell what one is looking at, even if unidentified or misidentified by the seller.
There are a number of things—no single one decisive by itself—to look for in assessing what a cameo is likely to be made of:
- Color: of layers or overall piece; whether layered, solid, swirled, mottled
- Grain: growth lines (or appearance of them)
- Edge: thick/thin; regular/variable, rounded/beveled/perpendicular to surface
- Curvature: back concave or flat. For bezel set pieces, is the bezel the same width all the way around or does it dip and rise to follow the curvature of the cameo, creating a saddle shape?
- Translucence: high/low/opaque (Examples)
- Size: Particularly a consideration when determining whether a piece is coral or conch shell. The branching structure of red coral limits the size of flat segments that can be cut from it. A large segment unmarred by predator damage is even rarer. Items that appear large at first glance often turn out to be constructed of multiple small pieces.
- Crispness of lines: Very rounded lines, including where figure meets ground, often indicate a molded piece.
- Chisel marks: Presence a strong indicator of a hand carved piece in natural material; absence of such marks, by itself, is not proof that a piece is not hand carved, but it is one factor to consider when distinguishing molded pieces from hand carved.
- Undercutting: Makers of vintage/antique molded cameos did not have the advantage of today’s flexible molds. Designs had to allow clean removal from the rigid mold. Presence of undercutting is a strong clue to hand carving, but lava a special case.
- Damage: Cracks & chips can reveal a lot about the material.
- Setting & Attachment: A hidden back when not necessary (as it usually is if cameo is set in a locket, e.g.) is frequently, although by no means always, an indicator of an artificial material, as is the attachment of the figure to the ground or the cameo to the setting with a rivet or brad. Quality of the setting relative to the quality of the cameo is another factor to consider, but is by no means decisive by itself. (Examples)
- Subject matter: While anything and everything seems to have been carved in helmet shell, carvers in other materials seem to have had, in general, a more limited subject range, with some subjects being seen much more frequently in a particular material (e.g., portraits of great artists in lava; noblewomen in hardstone).
Some properties can only be evaluated with the piece in hand:
- Texture: grainy/glassy (although some indication is typically discernible by glossy or matte appearance in photos)
- Coolness to touch
- Weight for size
The following pages will list points to look for when evaluating a cameo's material and help educate your eye through numerous examples of each material and its lookalikes.
Please note: Cameo Times cannot guarantee that following these guidelines will result in a correct identification in all cases. Artificial cameos are becoming increasingly realistic and there is no substitute for direct experience. It is always wise to check on the seller's return policy or other buyer protection measures before buying on line.
The most common misidentification of a cameo's material seen on eBay and similar sites concerns the paler shades of red coral, sometimes referred to as 'angel skin coral', and queen conch shell. A recent search of eBay listings for items with the terms 'angel skin coral cameo' in the title returned results that were overwhelmingly conch shell cameos or coral cameos in shades befitting only a very sunburned angel. The blurring of the distinction is not new and quite possibly not unintentional. In 1882, the firm Francati & Santamaria, preeminent purveyors of both raw materials for cameo cutting and gem engraving and of finished work, with establishments in England, Italy and France, advertised among their wares 'Pink Coral Shells', meaning Strombus gigas, or, as it is called now, Lobatus gigas, the queen conch.
True angel skin pieces are not common and the boundary separating this shade from its more sanguine relatives is highly subjective. The three pieces shown below are all genuine coral. Whether the color of each qualifies as 'angel skin' is up to the reader.
The material most often mistaken for coral is queen conch shell, a mollusk native to the waters of the Caribbean and around the US state of Florida. These large heavy shells were used as ballast by ships returning from delivering their cargo to the Americas. One can imagine how quickly cameo artisans would have taken to the thickness, sturdiness and pale shades of this material. Its resemblance to light pink coral (and the possibility of charging tourists coral prices) was surely not lost on them. It could regularly yield rough sections of predator damage-free material much larger than all but the rarest specimens of coral. The bases of the protective protuberances, 'horns', are especially thick.
Coral and seashells grow in two very different manners. Before they settle down for good in the apartment complex that is a coral colony, each little piece is a free swimming polyp. Apples don't fall far from the tree, and baby coral polyps aren't released far from the parent colony, but they may latch on at any spot on any colony in the neighborhood. The color of the little hard shell each produces is genetically determined. Red coral can vary in color from white to deep crimson. There is nothing compelling a polyp to join up with neighbors who share its place on the spectrum. Hence the jumbled, swirled coloration so often seen.
By contrast, conch shell is produced by a single organism through a process of accretion at the shell's lip of layered material specialized to the creature's survival needs: a thick outer layer to withstand the environment outside the shell; a smooth inner layer to provide a comfortable home for the mollusk within. Queen conch shells produce inner linings that range from nearly white to hot pink and an outer layer that is white. Most conch cameos are carved with a white figure or scene on a pink ground, but shells can be so large and thick, it is also possible to cut out sections that can be used in reverse, with the white layer for ground. These layers of color are the hallmark of conch.
Coral almost never looks like conch shell; conch shell, on the other hand, can do a very good imitation of coral. If one had only the photograph to the left to go by, an identification of coral would seem certain. And yet the front of the piece, shown to the right, displays the discrete layers of white and pink that confirm it as conch.
The higher value placed on coral easily leads us into temptation, into believing a conch piece is coral. Like most coral cameos, conch pieces are usually fairly thick and generally flat on back, although some are naturally a bit rippled. Both are nearly opaque, requiring a very strong light behind to show any translucence. As discussed later in the article, conch sometimes has pits and furrows on the back, just as many coral cameos do. Conch specimens with clearly delineated layers of white and pink are easily identified; those with less well organized coloration and those that are all a single solid pink or white are the teases.
As can be seen above in the photo showing the interior of a queen conch shell, the inner layer may have a high degree of variability in coloration, as well as fluctuations in the thickness of this layer. The artisan begins by slicing straight through the curved shell wall to remove a section. The natural irregularities of the shell would become fully apparent only as the piece was worked. The back of this Anchor of Hope piece bears some resemblance to the variegated look of some coral cameos; the clean white figure on the front, standing out crisply from its less decisive background, makes the determination of conch shell an easy one.
This lovely cameo of Diana, in shades of blush pink to white, could understandably be mistaken for angel skin coral, particularly from the front. However, the solid pink back tells a different story.
A bacchante draped in grape vine was a favorite subject of both coral and conch shell cutters. The thickness of these materials allowed for much higher relief than could be achieved in helmet shell or most hardstone (agate). Some of the most beautiful pieces we see are of the type shown here. They are also some of the most frequently misidentified as angel skin coral. Seen only from the front, this lady's composition is somewhat ambiguous; coral may produce small sections of color arranged in layers.
The more solid white of the back further confirms the layered nature of the piece. The side view clinches the matter: the piece is conch shell.
Before she was freed to become a beautiful brooch, she would have looked something like this:
In the example to the left, the conch shell carving goes from white to pink, then back to white.
The reader will notice that the pink of conch shell is not the same as the more salmon color of undyed coral. Angel skin coral is a shade of light red flirting with yellow; conch pink is cozying up to its neighbor in the other direction, blue. Another difference, not always detectable from photographs alone, is in the texture of the surfaces. Coral can take a very high polish, and pieces are typically buffed to a high degree of gloss over all surfaces, both figure and ground. Some of the most convincing artificial coral pieces are glass or Celluloid. The white layer of conch has a bisque china quality which artisans generally did not polish. The pink layer is like glazed porcelain and would have required little or no extra polishing to make it gleam.
The bracelet to the left is angel skin coral. The beads exhibit the haphazard arrangement of color characteristic of its kind.
It would be a forgivable sin (until you finish reading this) to think the necklace below is also coral.
Closer examination of individual beads, a few representative examples of which are shown here, tells the true story. The stratification of the color indicates a molluscan origin; the color suggests not conch but some other thick walled shell, probably helmet shell. The lip of even a medium sized specimen provides suitably thick material for cutting beads.
Conch shell beads are less common than ones cut from helmet shell. Again, it is highly tempting to see them as angel skin coral. But, the distinctive, slightly purplish, shade of pink identifies the beads to the left as conch shell.
The substance of the very pale, monochromatic cameo below, going by the color of the front alone, is ambiguous. Conch shell pieces can be solid pink or solid white. However, the glossy surface of the figure and the orange streaks on the back reveal it as coral.
On the other hand, while this piece is very similar in color, and was offered for sale as coral, the distinctly delineated strata show it is shell, like the beads shown above, probably from the Cassis family.
This coral Ceres exhibits a slight layering of color, a tinge of a richer shade of orange on her back and shoulder, and at places in her hair. However, once again the shade is a yellow pink, not the blue pink of conch. The glossy surfaces of the front and the almost wood grain appearance of the back settle the matter.
It is tempting to see a piece like this Diana as white coral. However, the matte finish of the entire piece, its relatively large size (almost 3 cm in height) and its solid, very pale pink back allow it to be identified as conch shell. On the cheek and neck, this piece also exhibits the faint striations not infrequently seen on conch cameos. While having the appearance of fine cracks or scratches that have become discolored, a fingernail will not catch in them and no amount of cleaning diminishes their appearance. Running nearly straight and in parallel, they probably mark growth increments and so are further evidence that the material is molusk-produced rather than coral.
As seen in the photos of the backs of a couple of the pieces shown at the beginning of the article, coral frequently has blackened pits, sometimes even small tunnels, made by marine predators with a taste for coral. As long as they do not mar the front, their presence can be seen as an asset: makers of artificial cameos meant to look like coral rarely go so far as to add black spots for verisimilitude. These black marks, although not proof positive by themselves, are evidence supporting an identification of genuine coral. (N.b., Celluloid pieces that have been subjected to the hot needle test will have small pits, occasionally blackened.)
Anyone who has picked up battered shells on Miami Beach will know that they, too, often show the gouges made by predators. Conch cameos carved with the white outer layer for background occasionally show such marks, another temptation to see conch as coral. Despite the appearance of the back, this Flora is, once again, conch shell.
This cameo, with its overall polished shine, looks very like angel skin coral at first glance. Closer inspection reveals several features that identify it as shell. Visible on the front are the darker, nearly parallel lines seen on some conch pieces. While in the photograph of the front the cameo appears to be a yellowish shade with tinges of orange, the back shows unmistakably as conch shell pink and white. The saddle shape of the bezel gives the final photographic clue; a query to the seller confirmed the piece is slightly curved, something not seen in coral pieces.
The term "hardstone" is a translation of the Italian pietra dura. While it is used widely in the world of cameos, it is not used by gemologists or mineralogists, being, perhaps, too general and loosely defined. Most of the materials comprised by this word are quartz in one of its many forms. Basalt, while certainly hard enough, comes to the surface in volcanic eruptions, so is usually classed, when used for a cameo, as "lava".
Most of the time, when we say "hardstone', we mean cameos such as this one of the Muse Urania (or perhaps, as the exposed breast suggests, Venus Urania) that have a figure or scene in one color raised above a background in a contrasting color. A generic term for material of this type is "layer stone". Another is "banded" or "layered agate". The word "agate' comes from a river in Sicily known to the ancients as the Achates. Sicily was long a source of the rough layered agate material highly desired by cameo cutters. (A beautifully illustrated, if awkwardly translated, extremely thorough treatise on Sardinian agate is available as a free pdf download from lulu.com.)
The principal constituent of agate is the microcrystalline quartz chalcedony. In its purest form chalcedony has little color, varying from translucent white to pale grey or blue. Highly porous, the color of chalcedony is readily altered by various means, some of which were known to the Romans. According to Walter Schumann, in Gemstones of the World, chalcedony was worn by the ancients as a talisman against depression and idiocy. They also carved it into cameos.
While there is no clear line dividing them, whether naturally occurring or treated—treatment is so commonplace jewellers rarely feel compelled to mention it—orange-red chalcedony is known as cornelian (in the U.S. "carnelian" is used more frequently); when it crosses the line toward a darker brown, as in the example above, it is called sard. The word "onyx" derives from the Greek for "fingernail". A cameo with a sard background and a white figure or scene that is translucent where the white layer has been pared down to just a breath on the surface is sardonyx. A bit of an oxymoron, perhaps, but chalcedony that has been dyed black—it does not occur this way naturally—is commonly known as black onyx or, much of the time, simply as onyx. Agate that has been tinted green is sometimes erroneously identified as chrysoprase or aventurine.
The two cameos above were almost certainly dyed to achieve the classic shade of cornelian red-orange. With only these photographs to judge by, it would be very difficult not to suspect them of being glass. Some additional clues are needed to make a proper assessment.
The nose and area around the eye of the bewreathed lady with the earring exhibits the translucence of onyx, allowing the cornelian to show through faintly. This effect can also be achieved in pâte sur pâte glass, where the artist painstakingly applies layer after layer of glass paste to build up the design. But she has another feature not seen in glass: the slight "aura" of the cornelian left around delicate areas such as the lips and tendrils of hair.
Her companion was cut with less finesse, but, despite the seemingly uniform color of the front, does show hints of layers when seen from the back. And yet this too is sometimes seen in glass, so does not allow for a decisive determination.
The last place to examine is the line where the figure meets the ground. Two-color glass cameos are made as two separate pieces which are then affixed together. There is complete separation of figure and ground. Sometimes it is even possible to catch a fingernail under the edge of the figure. In many hardstone pieces the line between the white and colored layers is not absolutely level, the carver must then cut into the background layer to keep the figure at an even height, and this can be seen at the interface, in some spots more than in others.
The ringstone-sized cameo below looks very like the two above; she even has the chipped nose so characteristic of hardstone cameos that have been living in an actively worn ring. But she is glass, constructed from two separate pieces. The edges of the white figure do not run into the ground at any point nor does the ground rise to meet her. A fingernail easily catches all around. Such cameos turn up set in rings of low karat gold, the precious metal lending them credibility.
These ladies must surely be hardstone? After all, the background color falls within the range of cornelian, the white figures gleam like polished stone. The one on the right has that "aura" of background layer by her mouth and under her chin, and both, despite their relatively large size, are so close to being flat the bezels do not follow the saddle shape usually required to accommodate shell cameos.
This is one of those cases in which photographs may not only fail to give the whole picture, but may be highly, no matter how unintentionally, deceptive. Both cameos are helmet shell. The translucency evident in the photographs taken from the back provides some evidence, but, depending on the thickness and color, hardstone can be nearly as translucent, as is the case with the hardstone maiden at right. Most of the time carvers in shell do not polish the white portion of the work; these did so. Most of the time a helmet shell cameo of any size would have enough curvature to require the bezel to undulate with its edges; these do not. Their true nature is more readily discerned when in the hand: while the lady on the left was cut by Luigi Michelini in a section of shell so thick the weight is not perceptibly different from what might be expected of stone, the lady with her hair caught up in a sakkos is much lighter in weight than would be a hardstone piece of comparable size; the back surfaces are subtly concave. When in doubt about a piece you are considering purchasing, it is advisable to inquire of the seller concerning weight for size and flatness/concavity of the cameo's reverse side.
Offered for sale in such a grimy state, this little green Diana was not readily distinguishable from glass. A bubble bath revealed her true, luminous appearance; an examination from the side confirmed her nature as agate.
The quartzes most of us recognize are the large crystal varieties, named by color, such as the amethyst and citrine shown here. These, along with smoky quartz, colorless quartz—"rock crystal"—and occasionally rose quartz, are sometimes cut as cameos. However, their uniform color makes them better suited to being engraved as intaglios.
If one is going mainly by pictures, pieces such as the three shown above pose a couple of major questions: How old is the piece? Is it genuinely stone or is it glass? The rock crystal Zeus-Serapis, in the collections of the Metropolitan Museum of Art, is as accomplished a work as anything done in our time; it dates to the 2nd or 3rd century C.E., as does the amethyst intaglio of the Emperor Caracalla, which was recut in the Byzantine period to convert him into St. Peter. The citrine hero is set in a 14K gold ring and is surrounded by what are probably genuine, if tiny, diamonds. One might therefore expect the cameo also to be what it appears to be. However, it is molded glass.
There is nothing like carbon dating that can distinguish an ancient piece from a modern one. Stone used by a gem engraver working today can be just as old as that used by the ancient Greek masters. In the 19th century there was such a rage for collecting ancient gems, supply, unsurprisingly, grew to meet demand. Gem engravers had always copied their predecessors. Now some began to sign with famous names from antiquity and to insinuate specious provenances. The uncertainty and lack of trust this engendered caused the bottom to fall out of the market and museum curators still argue over the age of some pieces. Since the 19th century fakes are now themselves antiques, they have an interest of their own. Our advice to those seeking genuine antiquities is caveat emptor. Sites such as eBay and most auction houses take no responsibility for the accuracy of the description of an item as dating to ancient times. It is better to work with an experienced and reputable dealer.
Since quartz and glass are both silicon based, a gem tester cannot always reliably differentiate between them. Uniform color and freedom from inclusions are generally prized in gems, but, as long as they do not mar the piece, irregularities can be assets in cameos and intaglios, since makers of glass simulants typically do not copy the natural material so exactly. Air bubble inclusions are a sure indicator of glass. The "citrine" cameo above has facets around the face and on the back. If it were natural stone, or even cut crystal, the edges where the facets meet would be crisp and sharp rather than blunt, which they are. The entire piece is too soft and rounded to have been hand cut; the low relief figure in a concavity is a strong indicator of pressed glass.
The nature of so-called "lava" cameos is a vexed subject, still very much under investigation by the editors. What follows is only the beginning of a more comprehensive article and our best understanding of the topic to date. Readers with additional insight into these pieces are invited—implored—to get in touch.
What better souvenir to bring back from a visit to Mt. Vesuvius and the buried towns of Pompeii and Herculaneum than a cameo carved from a sample of the materials the irascible volcano spewed out in 79 CE, choking the inhabitants with toxic gasses and interring them under meters of ash? We see many cameos offered for sale under the description "hand carved lava". "Lava" is a generic term for any solid material produced in a volcanic eruption, and some pieces so described show signs of having been molded rather than carved. This section will attempt to tease apart the cameos found in this category. One of its imitators, "dripstone", is taken up in a separate page following this one.
Carved Volcanic Material
One of the materials volcanoes sometimes produce in great quantity is basalt, a hard, typically dark, fine grained rock with varying mineralogical composition, which may include olivine. Basalt is the stuff of much of the Earth's crust.
This black and green cameo of Zeus fits the description of basalt. Certainly its mottled coloration suggests it is natural, undyed stone. The chisel scratches visible on the back attest to its hand manufacture. The range of subjects seen with any regularity executed in lava is much narrower than those in helmet shell; Zeus/Zeus-Serapis is part of the lava canon. Basalt cameos are sometimes misidentified as marble.
Another material volcanoes eject in explosive eruptions is known generically as "ash", fine mineral particles light enough to be carried on the wind. Created when the blast pulverizes the stone in its way—in geologist's terms it is "pyroclastic"—along with larger chunks of rock it settles around the volcano, solidifying into "tuff" or "tufa".
The lighter color and relative softness of so many "lava" cameos suggest that they are this substance, so abundant around Vesuvius, rather than the tougher, darker basalt. Saturn is another figure in the lava canon of subjects. This scythe bearing gentleman who has fissured in places along fault lines created by discrete clumps within the aggregated material is probably of this second type. The variegated color shows the piece has not been dyed; its lack of uniformity argues that it was carved, not molded.
The presence of undercutting, the removal of material so that the figure has some separation from the ground, is a good indicator that a lava cameo has undergone shaping by the use of hand tools. It is not a guarantee that the entire piece has been executed by hand. When the degree to which a piece has been worked in this way is extreme, when the carver has gone beyond outlining a profile to cutting his figures in such high relief that in places they are semi-detached from the background, it is safe to say the piece is hand carved. The two examples below are carved in solidified volcanic ash and were quite likely dyed to even out the color.
Modeled on Bertel Thorvaldsen's Cupid in the Underworld, the clever scamp is using his bow to yoke the three heads of Cerberus, the great hound who guards the portal to the realm of Hades. Here the carver has cut away as much as possible while still giving the piece enough stability to survive careful wearing.
With her goat familiar, this bacchante was not given quite so much definition by the maker, but it is still more than adequate to provide assurance of hand carving.
This cameo of Saint Joseph below—in case we did not recognize him by his flowering staff, the carver has considerately etched his name, S(anto) Giuseppe, on the back, something seen fairly often on lava cameos but not on cameos in other media—is in even lower relief, although there is a bit of air space beneath the head of the staff. Other points indicating carved lava: chisel scrapes to the back; detailed carving of the face when seen from the side; background layer squared off so that the edge is perpendicular to the front and back surfaces; and the ragged appearance of the chip on the edge. The lighter color the chip reveals this piece was dyed.
Although most pieces do not have the semi-detached elements that lead to a confident identification of carved lava, they can still be carved in a manner that, taken with other signs, indicates they are also hand worked volcanic material. The sharp, incised lines of this cameo of Cybele/Tyche would not be seen in a molded piece. The scoring to the crown of the head could have been added as a finishing touch to a molded piece, but the raised turrets of her mural crown could not have been created by a rigid mold.
Omphale has lost some of her nose and some of her color, but the wildness of her mingled mane/hair and the definition around the lion's mouth and teeth are clearly hand work. The indentation below her lower lip is by itself good evidence for the craftsman.
This little plaque of a praying boy was offered for sale as lava. However, it is noticeably lighter in the hand than would be a genuine lava piece of the same size. The back gives the game away: the embedded wire hanger had to have been placed while the material was liquid. Additional evidence for the true nature of the piece was given accidentally when the plaque was knocked to the floor: not only did it not so much as chip, it bounced. Although the material is undoubtedly a modern synthetic, the mold used to cast it may have been made from a genuine lava carving. However, the one thing he is not is lava.
The French make plaques, frequently religious subjects for personal devotions, in white materials that are variously described as meerschaum, pipe clay, chalk, calcaire pétrifié (see the section on limestone) or carved plaster. Alabaster and soapstone are also sometimes proposed as the material used. As far as we have been able to determine to date, more than one material is employed in their making. Some do seem to be actual meerschaum; these are very light in the hand.
When in doubt over an on line purchase, ask questions, request more photos, make sure the transaction carries some sort of buyer protection.
There is a type of cameo seen fairly often, typically described as vintage/antique hand carved "lava" or "meerschaum", that is actually molded in what geologists call "dripstone", the calcareous deposit left when calcium carbonate-rich water dries. Seashells are made primarily of calcium carbonate; limestone is made by the sedimentation of countless small shelled organisms that die, sink to the ocean bottom, and leave their tiny deposit of calcium to combine with the others, until time and pressure convert them to stone on the sea floor.
Sometimes the restlessness of the earth brings these deposits to the surface, where weather and running water reshape them into caves. The icicle-like stalactites that hang from the roof of some caves, and their stalagmite counterparts on the floor below, are composed of dripstone. Another way that calcium carbonate saturated water comes to the surface is in volcanically warmed hot springs flowing through a limestone substrate, such as the Fontaines Pétrifiantes of Saint-Nectaire, in the Auvergne region of France. Just as cameos carved in lava are treasured souvenirs of Mt. Vesuvius and the buried Pompeii, cameos created using limestone laden water have long been brought back by visitors to cave systems, religious grottoes and to hot springs.
To create these pieces of what the French term calcaire pétrifié, the water carrying limestone particles is channeled over a structure resembling a ladder. As the water flows down from step to step, the larger, heavier particles drop out; water reaching the bottom carries only the finest, lightest grains. The mold is started at the bottom of the ladder so that the outer layer of the cameo is made of very fine grained material. Once this layer has been laid down, the piece is moved up the ladder, gradually being filled in with ever coarser grained material. (For a detailed description of the process, click here.)
As the piece dries, the material contracts & small crystals form. This piece, still being made at Saint-Nectaire, shows the characteristic concavity on the back, which corresponds in outline to the figure on the front (the photo to the right of the one of the concavity has been reversed to make this correspondence easier to see) and is lined with minute crystals similar to those in a geode.
While the front is fairly smooth, the back surface is grainy and coarse. Lava varies in the fineness of the grain, but each individual piece will have the same texture front and back; genuine hand carved pieces never display a crystal lined depression of this sort.
The tendency of dripwater to form calcite crystals as it dries leads to such pieces being more vulnerable to fracture than their lava cousins. The piece shown above has lost some material from the top edge, not visible from the front, in what looks more like a spontaneous crumbling than the result of any trauma. These require gentle and, to minimize discoloration due to skin oil, infrequent handling. The material is highly porous, so care is needed when cleaning or exposing to any liquid other than plain water. Given that each one started out as a limestone solution, care should be taken even with that, lest they return to their original state. Although we have not seen a case of this, the calcium carbonate nature of dripstone may mean it is also vulnerable to "Byne's Disease".
The deep crease on the back of the Ceres (far left) follows the line of the wheat stalk wreath on her head. She has the name Reverchon at the truncation line; evidently the mold that produced this piece was taken from a work by that French family of gem cutters.
This elaborate scene, framed for hanging, was a souvenir from the extensive limestone caves on Gibraltar. We know because the thoughtful traveler pasted a note to the back.
This cameo is formed from the water that drips from and forms the Stalactites in the Caves of Gibraltar. Forming in an Intaglio Matrix, it takes about a month to form and harden one of this size.
Gibraltar was not the only tourist attraction to offer dripstone mementos of your visit. Here, a trio of beauties from the grotto in Royat, France. Although Naples has an extensive system of caves, much enlarged by human activity, we have yet to see a dripstone specimen that could be positively identified as having originated in Italy. Cameos such as these are not lava, they are not hand carved, and they are not souvenirs of Vesuvius or Pompeii. Those with religious subjects seem to come primarily from France and are often misidentified as meerschaum or pipe clay.
The Hunterian Museum of the University of Glasgow holds this portrait medallion of the Roman emperor Galba. While they do not use the term "dripstone", they do describe the piece as calcite, the mineral of dripstone, and as a speleothem, the product of a cave. A photograph of the back would undoubtedly show some degree of indentation.