To clarify and remove any possible ambiguity from a trade term that is used to name or classify products in the jewellery industry, CIBJO, came up with a new expression during a Pearl Commission meeting held in its 2016 Congress in Yerevan, Armenia. This new expression that would collectively refer to any gem material derived from living organisms was agreed to be "biogenic", that basically relates to a biological origin.
The expression organic was maintained but it would be used for biogenic gem materials that are essentially composed by organic matter or organic molecules, as defined in chemistry. Under the new terminology, organic gem materials now include, for example, tortoiseshell, horn, black coral, copal and the so-called vegetable "ivory", and, by its own definition, rule out the gem materials that are essentially composed by biomineralised substances, like calcium carbonate in the form of aragonite or calcite, including pearls, cultured pearls, mother-of-pearl, shells and precious corals.
For the sake of clarity, although fossils, like amber, ammolite, opalised molluscs, silicified wood and mammoth ivory, as well as other materials of biological origin found in a geological context like jet (not technically a fossil) may have had in their origin a living organism, these are not considered biogenic gem materials strictum sensum.
Instead of elaborating on a selection of gem materials of biological origin, of which cultured pearls are probably the most relevant ones in the jewellery trade today, it was decided that a conservation perspective was in order under the spirit of United Nations Decade on Biodiversity. This means that, along with other gem materials, the vast majority natural and cultured pearls will not be covered here as well as the historically relevant precious coral species of the Mediterranean since the species that produce them are not listed in the Convention on International Trade of Endangered Species (CITES), as per the last Conference of Parties held in Geneva in 2019 (www.cites.org).
CITES APPENDIX I
CITES APPENDIX II
CITES APPENDIX III
CITES LISTED SPECIES
APPENDIX I
Rhinoplax vigil (Forster, 1781)
This large tropical bird of the Bucerotidae family that lives in Asia namely in Indonesia, Thailand, Malaysia and Myanmar, known as the helmeted hornbill, develops, especially in the males, a large beak that has a yellow to red keratinous thick covering known in the trade as hornbill ivory. It has been known as a gem material at least since the Ming dynasty in China. The trade name of this gem material includes the word "ivory" which is considered a misnomer since it is not a tooth from a mammal but rather a keratinous covering over a bone structure. Nevertheless, as one may verify in many particular situations in our trade, tradition has crystallized this trade term, being therefore generally accepted as it is.
Photo © Skullsite
Rhinocerontidae spp.
The few existing species of rhinos of the Rhinocero- ntidae family in Africa and Asia, including the white rhinoceros, Ceratotherium simum (Burchell, 1817), the Sumatran rhinoceros, Dicerorhinus sumatrensis (G. Fischer, 1814), the black rhinoceros, Diceros bicornis, (Linnaeus, 1758), the Javan rhinoceros, Rhinoceros sondaicus (Desmarest, 1822) and the great Indian rhinoceros, Rhinoceros unicornis (Linnaeus, 1758), develop a rather typical protuberance above their nose, sometimes a rather long one up to 150 cm long, that is commonly known as a horn, more specifically rhino horn. Again, this trade name carries another technical terminology inaccuracy since this material is not exactly horn, as we may see in bovids, but rather an agglomerate of long hardened hairs without a bone internal structure. Again, tradition has made this trade term generally accepted.
Photo: Libation cup, Jiangsu, China. Rhino horn mounted on silver filigree (Manila?) 17th century, second half. Private Collection, OnShot/Rui Carvalho. Museu do Oriente
Physeter macrocephalus (Linnaeus, 1758)
The large cachalot, also known as sperm whale, is the largest existing toothed whale with males easily reaching 15 meters long, living in almost all oceans and latitudes. The 32 to 52 teeth on the lower jaw can grow up to 25 cm long and have been used as sperm whale ivory in tools and decorative arts for centuries as a by-product of the whale hunting for their meat and oils. New England sailors while on board whale ships in the 19th century used to kill time by carving these whale teeth and also whale bones, a technique that would eventually become known as scrimshaw.
Photo, scrimshaw © Peter Cafe Museum
Loxodonta spp. & Elephas spp.
African elephants, Loxodonta Africana (Blumenbach, 1797) and Loxodonta cyclotis (Matschie, 1900) and Asian elephants, Elephas maximus (Linnaeus 1758) that develop a sometimes very long pair of teeth, especially the males, are among the most controversial sources of ivory, having been at the centre of rather intense discussions in several countries on their trade even as antiques. The fact is that the species are listed in Appendix I, with some exceptions in certain geographies, and therefore deserve mentioned here.
Elephant ivory has been the most used type of ivory in the decorative arts, marquetry or musical instrument manufacture, due to its size, texture and carving adequacy. Distinguishing elephant ivory from other types of ivory from other living mammals (e.g. hippo, cachalot, warthog, orca, walrus) can be tricky if one does not have enough visual experience. More difficult is separating ivory from living elephants from the extinct mammoths, notably the woolly mammoth Mammothus primogenius (Blumenbach, 1799). Al- though a careful observation of the engine turned growth structures seen perpendicular to the growth direction, known as Schreger lines, might give fairly good indications in most cases, DNA fingerprinting and, more recently, carbon-14 dating has been suggested as a test to separate century-old ivory of elephants from a fossil material from other species, typically older than 10,000 years.
In the last CITES CoP in 2019, a suggestion was made to include the woolly mammoth in CITES Appendix II. Although the species needs no protection since it has been extinct for thousands of years, the purpose was to fight illegal trade in living elephants by preventing "laundering" or mislabelling of elephant ivory. The proposal was, however, not approved.
Photo: SIngalo-Portuguese, 16th century, Sri Lanka © PAB
Eretmochelys imbricata (Linnaeus, 1766)
The hawksbill sea turtle has been the most common source of scutes for the decorative arts that are known in the trade as tortoiseshell, another misnomer since the animal is not technically a tortoise but a turtle. Other marine species like the green turtle, Chelonia midas (Linnaeus, 1758) or the log- gerhead turtle, Caretta caretta (Linnaeus, 1758), have also been used but to a much lesser extent since their individual scutes are not as good quality as the hawksbill’s.
Tortoiseshell, a natural plastic (a polymer, just like rubber or shellac that are also technically natural plastics), is typ- ically light yellow with dark brown areas when it is from the dorsal carapace of the turtle. The ventral protection scutes are, on the other hand, of an homogeneous yellow colour and are much thinner that the dorsal counterparts, being known in the trade as "blond tortoiseshell". Individual dorsal scutes are usually rather thin (up to 12 mm, however thicker than other turtles’ scutes) and somewhat large (averaging 20 cm in maximum length) and it was the outstanding thermo- plastic properties of this attractive material that enabled craftsman to work them in intricate shapes and sizable artefacts of marquetry and other decorative objects.
Photo: 16th centuryCasquet, tortoiseshell and silver mountings. Gujarat, India. Mid-16th century © Diocese de Beja