(Fr-écaille de tortue; Ger-SchildpattNor-skilpaddeskall; Rus- черепашья  чешуя)

A. Tortoise shell card case (height - 9.4 cm) with gold and silver inlaid floral accents. An enclosed notebook had a first page inscription written in French dated 18/01/74 [= 18 January 1874].  (© photo by Darlene Register, from  

DESCRIPTION: Phylum, Chordata; class, Reptilia; order, Testudines; family, Cheloniidae: Tortoise shell is composed chiefly of β-keratin. 
Colors - typically light yellowish tan, mottled dark brown to nearly black;  rarely reddish
    H.   ~2½  <<  an example of plate-like keratin-rich material.
    S.G.    ~1.29  <<  an example of plate-like keratin-rich material.
    Light transmission - transparent to translucent
    Luster - pearly to waxy
    Breakage - irregular
    Miscellaneous - sectile;  slightly flexible; chalky blue fluorescence of lighter zones with long-wave ultraviolet radiation; when burned it emits  an odor like burning hair -- BUT, see statement about the hot-point test in glossary.  Dark zones are commonly bordered by zones that can be seen readily using a microscope and in most cases by using only a 10x hand lens to consist of small spheroidal spots.

OTHER NAMES: This material is frequently referred to by the single word tortoiseshell.  also:
USES: Tortoise shell, in most cases the top shell of sea turtles, has been used for adornment for untold centuries -- e.g., for bracelets, earrings, necklaces, pendants (commonly including their chains) and rings.  Some pieces have been carved, engraved, etched or merely scratched artistically.  It also has been used for such things as small boxes, fine toilet ware (combs, brush and nail file handles, etc.), frames for eyeglasses, tableware, lampshades and accessories for musical instruments (e.g., guitar picks).  In addition, especially in the past, tortoise shell was used as a veneer or inlay for decorative objects, including furniture. See statement re current use directly following the SIIMULANTS subheading.

B. Tortoise shell bracelet (diameter ~ 6 cm) atop mirror.   (©  photo by Dick Dietrich)

C. Tortoise shellThis stamp of the Republic of the Maldives (1.30 Maldivian rufiyaa, dated 11 November 1979) features, a flat section of polished tortise shell in the left panel and two bracelets, two rings, a container with lid, and a dish made of tortoise shell in the right panel.  photo of stamp by Richard Busch, reproduced by permission  

Tortoise shell simulant.  Pick guard, made of "Tor-Tis" by Turtle works, with a vine-shaped inlay of "mother-of-pearl and pale abalone."  photo by Jeff Mosby, from  

OCCURRENCES & NOTEWORTHY LOCALITIES: Most tortoise shell in the marketplace has come from the protective overlapping dorsal plates (scutes) of hawksbill sea turtles (Eretmochelys imbricata (Linnaeus, 1766));  good descriptions of the plates, of which there are 13, are given by Smith and Phillips (1962, p. 495) and Webster (1975, p. 532 -- see especially Figure 24.12).  Some tortoise shell, however, is said to have come from the green sea turtle (Chelonia mydas (Linnaeus, 1758)), and lesser amounts have come from the loggerhead sea turtle (Caretta caretta (Linnaeus, 1758)). These turtles live in the tropical areas of the Pacific and Atlantic oceans.  Much of the supply of tortoise shell has come from the Celebes, Moluccas and New Guinea, but China, India, Africa and Australia are also well known sources.  See also the last paragraph of the REMARKS.

REMARKS:  So far as the origin of the term tortoise, Harper (2002) give the following: "1552, altered (perhaps by infl. of porpoise) from M.E.[Middle English] tortuse (1495), tortuce (1440), tortuge (1398), from M.L.[Medieval Latin] tortuca (c.1255), perhaps from L.L.[Late Latin] tartaruchus "of the underworld" ...[But,] Others propose a connection with L.[Classical Latin] tortus "twisted," based on the shape of the feet. The classical L[atin]. word was testudo, from testa "shell." First record of tortoise shell as a coloring pattern is from 1782."

The plates are separated from the tortoise's skeleton.  The plates -- tortoise shell -- is thermoplastic;  but, this property seems to be transitory and virtually lost as the material becomes brittle with  time.  Consequently, to utilize the advantages this property affords, certain procedures have to be employed while the tortoise shell is so-to-speak fresh;  and, even then, care has to be taken during the required heating because overheating will melt the shell to a useless black mass (which, by the way, smells like burnt hair).  In any case, thermoplasticity has led to several desired end-products:  Molded shapes;  surfaces with finely carved appearances, which are made by pressing the heated shell into a mold or pressing a given shape into the heated shell;  piqué -- i.e., tortoise shell with inlays, typically small, of silver, gold, mother-of-pearl (etc.) -- that are made by pressing small pieces of the inlay material into the tortoise shell while it is heated (Figure A may be an example);  the joining of small pieces (even scraps) to produce large pieces and/or laminated masses; etc. All these processes require heat, usually using near-boiling water, and, when lamination is the desired end-product, pressure must also be applied.
      For some purposes (e.g., inlay) tortoise shell has had its inner surface colored to give it a "dark red or golden hue.  To achieve a dark red, the inner surface ... is painted with a liquid obtained by mixing red lead or cinnabar with glue.  To obtain a golden colour,  one must use gilt leaf or some other material." (Ministry..., 1986)  Gold leaf has also been placed under thin tortoise shell veneer to make it appear more luminous.

Tortoise shell objects should not be exposed to direct sunlight over any extended period.  Such exposure may result in their taking on an unattractive gray hue.  In any case, heat -- either by exposure to the sun or from other sources -- is said possibly to have cause damage -- e.g., warping (Child, 2006) Also, I have been told (but to date have been unable to confirm the possibility) that tortoise shell is susceptible to insect damage.  On the positive side, broken and scratched pieces can often be made to look like new relatively easily because of their thermoplasticity.

Former recorded uses of tortoise shells include the following: 1. "The Indian Ocean produces turtles of such size that the natives roof dwelling-houses with the expanse of a single shell, and use them as boats in sailing, especially among the islands of the Red Sea." (Pliny, Book IX, chapter 12, paragraph 1).   2. The “Aboriginal Testudo” –  i.e., “A kind of musical instrument.  a species of lyre; – so called in allusion to the lyre of Mercury, fabled to have been made of the shell of a tortoise” (Webster, 1913 - see ARTFL Project..., 1997) –  was used in the Yucatan region of Central America  (Southey, 1950, p.570 - after Herrera, 1625).   3. In the area of the Masaras, south of Victoria Falls (Africa), Baldwin (1863, p387-388) recorded in his diary, "a drink of muddy water ... out of a dirty tortoise-shell, ... serves for breakfast, dinner, and supper.”    [and]   4. At least as early as 1644, "curiosities of ivory and tortoise-shells," apparently from the East Indies, were sold at Fort Pollet, which is on the English Channel near Dieppe, northeastern France (Evelyn, c1901, 21st March 1644 entry).

"In 1995, the Government of Zanzibar, Tanzania, destroyed Souvenirs made from sea turtle products, in an effort to eliminate a trade that ... [was] escalating as the number of tourists to the island was growing.  .... The scarcity of marine turtles combined with strict controls on the trade in turtles has now greatly reduced the size of this trade.  Japan is largely responsible for driving this trade, importing tens of thousands of hawksbill turtles for tortoiseshell trinkets.  Stuffed turtles, turtle skin goods, live hatchlings are all sold illegally in souvenir shops.  Many turtles that are taken for souvenirs have not reached sexual maturity, which can have significant consequences for future breeding population numbers." (UN Atlas of the oceans, 2000-2002).  Applicable CITES restrictions should be reviewed by anyone interested in procuring anything made of tortoise shell. 

SIMULANTS: Simulants and what perhaps are best termed semi-simulants (i.e., pieces consisting of thin veneers of tortoise shell cemented on, for example, celluloid) have been on the market for several decades. The original impetus for production of these simulants appears to have related to the fact that natural tortoise shell was relatively expensive.  More recently, however, simulants have become virtually the only material available legally in international trade because the hawksbill and other sea turtles have been declared endangered species.  Relatively sophisticated means, some that require state-of-the-art equipment, used to distinguish tortoise shell from its simulants are given by Hainschwang & Leggio (2006).

Acetate -  This designation -- probably referring to cellulose acetate -- has been recorded as being used as a tortoise shell simulant. - [Although I have seen only photographs, I suspect that observation would suffice to distinguish it as a simulant.].

***Acrylic - so-designated simulant, which probably is also the material called resin. - [Although I have seen only photographs, I suspect that observation would suffice to distinguish it as a simulant.].

Caribou hooves - "In the Eskimo village of Kivalina, on the eastern coast of Alaska, natives started a home industry by making jewellery from the hooves of caribou.  The material takes a high polish and to some extent resembles tortoise-shell." (Webster, 1975, p. 535) - [I suspect that close observation suffices.].

***Ceramic - ceramic with an overall surficial appearance of tortoise shell. - [Observation suffices.  Also, this simulant has superior hardness.].

***Faux tortoiseshell - a fortunate designation in that it is not misleading so no checking is necessary.

***Glass - glass colored to resemble tortoise shell. - [Observation suffices. Also, glass has a superior hardness.].

Horn - stained horn -- e.g., buffalo horn -- is noted as a substitute by Smith and Phillips (1962). - [Lack of the dark zones bordered by what appear to be groups of subspherical reddish zones, mentioned under the DESCRIPTION, distinguishes horn from tortoise shell.  But, for some pieces differentiation may require consulting a professional expert.].

***"Mixtures of resins and tortoise shell and resin-stabilized tortoise shell ... [which show] properties intermediate between tortoise shell and plastic ...[exhibit] properties intermediate between tortoise shell and plastic."  (Hainschwang & Leggio, 2006, p.49)  Also, like metals and alloys (i.e., Not tortoise simulants), resin replicas of turtles, some with patinated bronze finishes, have been produced;  and, some of them are relatively large and marketed for use as garden or landscape accents.

***Mock tortoise -- material so designated, but not otherwise identified, has been use for such things as handles on safety razors and shaving brushes. - [Close examination of the texture should suffice.]

***Plastics - Some of these plastics are easily confused with tortoise shell "at first look."  Anderson(1980, p.378) lists the following plastics (followed by their specific gravity values) as having been used as "imitation tortoiseshell": Casein (1.33 + .01), Cellon (1.26), Rhodoid (1.28) and Celluloid (1.38 -1.42).  His data indicate that two of these simulants have noticeably higher specific gravity values than that of typical Tortoise shell (S.G. ~1.29), whereas the other two have values that would make them difficult to distinguish from tortoiseshell by using any of the common methods used to determine density.  He also refers to the already mentioned fact that "the dark patches of tortoiseshell will be seen to contain swarms of spherical reddish particles, whereas in the plastics the imitative dark patches lack this structure, and the edges of the dark areas are more sharply defined. [In addition, he adds] Chips of tortoiseshell fuse to a black mass smelling of burning hair, while casein plastics char and smell of burnt milk."   Bakelite (S.G. 1.36) and galaith (= casein formaldehyde, S.G. 1.33 + .01) are two other plastics known to have been used as tortoise shell simulants. - [The just mentioned characteristics also provide means to differentiate these plastics from tortoise shell;  in addition, bubbles, if present, are indicative of plastics and tortoise shell emits a burning hair aura when heated with a hot point whereas most plastics give an acrid odor, and celluloid may combust, sometimes rather vigorously/dangerously(!!!).].

***Polyester -
any one of several synthetic polymers, some of which are designated resin, produced to resemble tortoise shell. - [Observation  suffices.].

***"Tor-Tis" - a remarkably realistic appearing faux tortoiseshell marketed by TurtleWorks, which I have seen only in photographs (see Figure C). - [I have been unable to find the composition or determine the properties.].

***Whieldon's tortoiseshell ware - Never considered to be a simulant per se, but noteworthy here,  this early 19th century Staffordshire ware was originated by Thomas Whieldon.  It is said to have been given its tortoise shell appearance by "dusting" brown and straw colors, to produce blurred areas, atop a cream-colored base followed by application of a lead glaze to give it the desired sheen.  Pieces produced included bowls, coffee pots, creamers, cups and saucers, dessert services, sugar bowls and teapots.  It is perhaps of interest that for a relatively short period, Whieldon and Josiah Wedgwood were partners in making tortoiseshell wares.

REPLICAS:  Small replicas of turtles have been fashioned from diverse metallic materials – e.g., copper, gold, silver, "porcelon," pewter and other alloys – for use in jewelry such as brooches, bracelets, bracelets, pendants and pins. Some of these replicas are bedecked with gemstones such as lapis lazuli and/or zoogems such as mother-of-pearl, and severak are enameled.  Similarly appearing replicas have been produced for use as the ends of chain pulls for frans and lights.  Larger, but similarly constituted replicas have been made to market as, for example, music boxes --  I have seen one that one plays Brahms' "Lullaby"  when opened.

Fetishes and other carvings shaped to resemble tortoises are made of ceramic materials, cast in aluminum or iron, and carved from gemrocks such as marble (e.g., Picasso marble), petoskey stone
(see Fossiliferous Rocks entry in the GemRocks folder on this web site), resin (in some cases containing admixed particles of stones or rock), and diverse species of wood (some are rather lifelike carvings whereas others are painted and/or bedecked with gemstones). These replicas have such diverse uses as garden "sculptures," stepping stones and roles in "wall art."  One of the more interesting replicas of animals considered in entries on the web site is a 5 x 14-inches fturtle-shaped nightlight that gives a 360-degree view of the sky -- stars and constellations -- on the walls of the bedroom (or wherever it is placed);  several well-known constellations, including the Big Dipper and Pegasus are among those shown;  powered by batteries, the light  turns off automatically after about three quarters of an hour. 

Tortoises created by applying the "centuries-old millefiori, or 'thousand flowers,' technique" have produced what one might characterize as objets d'art;  they are esp
ecially eye-appealing, but hardly warrant the designation replica because only their overall shapes resemble tortoises.

Footstools shaped like tortoises, some with their leather tops scored or otherwise treated so they take on tortoise shell-like patterns and colors, are marketed rather widely.

| Top | Home |

R.V. Dietrich © 2015
Last update: 12 January
web page created by Emmett Mason