Nautilus Pearls

  • All shelled mollusks are technically capable of producing pearls. However, most of the natural pearls we come across have their origin from two main classes of mollusks - the Bivalvia and the Gastropoda. Some of the bivalve mollusks that commonly produce pearls are oysters, clams, mussels, scallops and pen shells. Among the gastropod mollusks that produce pearls are sea-snails like queen conch, horse conch, abalone sea-snails, melo-melo sea-snails etc.
    Other classes of shelled-mollusks include Polyplacophora (Chitons) living on rocky inter-tidal and sub-tidal zones; Monoplacophora - an ancient class of mollusks with cap-like shells, living on the seabed at depths of 1,800-7,000 meters; Scaphopoda (tusk shells) living on the seabed at depths of 6,000-7,000 meters and the Cephalopoda - consisting of two sub-classes, the Coleoidea which includes octopuses, squids, cuttlefish in which the shell is absent or internalized (cuttlefish), argonauts in which the shell is retained and the sub-class Nautiloidea represented by Nautilus and Allonautilus, primitive cephalopods in which the shell is still retained. The Genus Nautilus belongs to the Nautilidae, a primitive cephalopod family/order, of which most of the species are extinct, and only six species survive to this day. The surviving Nautilus species commonly referred to as Chambered Nautilus still retain their spiral shells and remain unchanged for millions of years and are often referred to as "living fossils."
    The existence of pearls in Monoplacophora and Scaphoda have not been reported not because they are absent, but due to the extreme depths at which they exist making their collection very difficult. In the case of the shelled Cephalopods, such as the Argonauts that cling to floating objects in the sea, both inanimate and living objects such as jelly-fishes, and the six different species of Nautilus, that are found only in the Indo-Pacific at depths of 100-200 meters and a maximum of 800 meters, beyond which they implode causing instant death, extremely rare occurrence of pearls have been reported, and are found in the collection of connoisseurs.
    The first report of the discovery of a Nautiulus pearl came in October 1912, in the form of a letter from H. Lyster Jameson accompanied by a photograph of the pearl, and published in the October 1912 issue of the Nature Magazine. This pearl was discovered by a cuttlefish and squid fisherman, in the waters of the Sulu Archipelago from the species Nautilus pompilus, the largest of the Nautilus species that can attain a maximum diameter of 30 cm, and surrendered to the Sultan of Sulu. Only a handful of Nautilus pearls are found in the world today, and two of this rare pearls are believed to be in the collection of the Emir of Qatar. Several of these pearls are found in the collection of Thomas Hochstrasser and depicted in his website with the following URL :-
    Out of the 7 Nautilus pearls shown in the website all are white in color. The pearls appear to be porcellaneous and at least two of them appear to have a flame-like structure similar to conch pearls. 4 of the pearls are spherical in shape, 1 pearl near-spherical or button-shaped, 1 pearl shaped like a cucumber, and 1 pearl baroque shaped. The largest pearl is a spherical pearl with a diameter of 22.7 mm and weight of 59.3 carats; perhaps the largest Nautilus pearl in the world.
    The following thumbnails are in order :-
    1) Nautilus species from Palau micronesia.
    2) A Nautilus pearl
    3) Nautilus shell cut in half, showing chambers arranged in logarithmic spiral and the nacreous interior of the shell
    4) 59.3-carat Nautilus pearl - perhaps the largest Nautilus pearl in the world.

  • Welcome aboard ashleeduhe and thanks for your contribution. We hope you would be a regular contributor to our fora. After explaining what true Nautilus pearls are, the next logical step would be to consider a category of "pearls" that are sometimes associated with jewelry, and referred to as Nautilus "Pearls" / Nautilus "Mabe Pearls" / Osmena/Osmina Pearls. You have correctly guided us to this topic by your contribution.
    Osmena/Osmina "Pearls" are not true Nautilus pearls but a pearl substitute derived from the inner spiral of the nautilus logarithmic spiral shell. The Nautilus shell wall is made up of two layers, an outer matte white layer and an inner blue-gray shiny iridescent layer, composed of conchiolin (protein) and aragonite (non-protein, crystalline calcium carbonate). In other words the inner layer is made of nacre, like the mother-of-pearl of oysters and mussels.
    In fashioning an Osmena/Osmina "pearl" the inner spiral of the nautilus shell is cut off to give a round or oval-shaped portion, that is polished until it reveals the inner iridescent nacreous layer. The empty chambers of the cut shell is filled with resin and sealed with a piece of mother of pearl to give a dome-shaped, flat-backed, cabochon-shaped iridescent Osmena/Osmina pearl, that has the luster and iridescence of true nacreous pearls, and a natural silver-blue color without any dye or enhancement. Due to their button shape with a flat back, Osmina Nautilus pearls are ideal for settings in jewelry such as rings and earrings, in which the flat back is concealed and the lustrous dome-shaped part is exposed.
    The thumbnail below is that of an original Osmena pearl marketed by Leeleeko Jewelry based in the U.S.

  • If as you said the Nautilus shell wall is made up of two layers, an outer matte, white layer and an inner blue-gray shiny nacreous layer, made of conchiolin and aragonite, why are Nautilus pearls non-nacreous and porcellaneous, with a matte-like appearance lacking the iridescence of nacreous pearls?

  • Quote from rashid

    If as you said the Nautilus shell wall is made up of two layers, an outer matte, white layer and an inner blue-gray shiny nacreous layer, made of conchiolin and aragonite, why are Nautilus pearls non-nacreous and porcellaneous, with a matte-like appearance lacking the iridescence of nacreous pearls?

    CIBJO, the World Jewelry Confederation defines the term "Mother-of-pearl" as follows :-
    the smooth, hard, iridescent coating on the inner surface of the shell of some species of molluscs, composed of microscopic crystals of aragonite and/or calcite (a form of calcium carbonate) deposited in thin layers with organic conchiolin; scientifically known as nacre (5.130). Usually pearls produced by the particular mollusc have the same colour, composition and general quality as the mother-of-pearl of the particular mollusc.

    Hence, as the Nautilus shell has an inner blue-gray iridescent mother-of-pearl layer, it is reasonable to assume that any pearls produced by the Nautilus mollusc would also be nacreous having the luster and iridescence of nacreous pearls. However, in actual fact the pearls produced by Nautilus are non-nacreous, with a porcellaneous sheen and sometimes having a flame structure, similar to Conch pearls and Melo pearls. According to the CIBJO definition of "mother-of-pearl" usually pearls produced by a mollusc have the same color, composition and general quality as the "mother-of-pearl" of the mollusc. This is true for saltwater pearls produced by oysters, freshwater pearls produced by mussels and Abalone pearls produced by the abalone snail. Hence, the situation in Nautilus pearls, where the mother-of-pearl is nacreous, but the pearl produced non-nacreous, seems to be an exception to this general rule.

  • Argonauts and Nautiluses are distantly related by virtue of belonging to the same class of Mollusks, the Cephalopoda. However, they belong to different subclasses, the Coleoidea and the Nautiloidea respectively. The sub-class Nautiloidea that include Nautilus and Allonautilus, are primitive cephalopods in which the shell is still retained.
    The subclass Coleoidea which are more advanced Cephalopods, include octopuses, squids and cuttlefish in which the shell is absent or internalized (cuttlefish). Argonauts are a type of Octopus coming under the Order Octopoda, with a bilaterally symmetrical body like other Cephalopods, a pair of eyes and four pairs of arms. Octopuses have no internal or external skeleton, but some species of Octupuses in the sub-order Cirrina have two fins and an internal shell, and in the sub-order Incirrina and family Argonautidae, to which Argonauts belong, the females produce a laterally compressed calcareous egg case commonly referred to as a "shell" which can reach a maximum diameter of 30 cm in the largest species Argonauta argo and around 7 cm for the smallest species Argonauta bottgeri. The eggcase is secreted by the tips of the female argonaut's two greatly expanded dorsal tentacles before egg laying. After depositing her eggs in the eggcase , the female takes shelter in it, with only her head and tentacles protruding out. These "shells" are composed of calcite and not aragonite as in other mollusk shells. Both calcite and aragonite are crystalline forms of calcium carbonate. The eggcase also contains air that the animal captures at the surface of the water, which helps in its buoyancy as it floats around closer to the surface of the sea. Some species like Argonauta hians cling to floating objects on the surface of the sea, including other argonauts and jelly fish.
    The eggcase of Argonauts curiously resemble resemble the shells of the chambered Nautilus and the extinct ammonites. The "shell" has a double keel fringed by two rows of alternating tubercles. The sides of the "shell" are ribbed radiating from its notch.
    The following thumbnails are in order :-
    1) Female Argonauta nodosa, with eggcase being secreted by the dorsal tentacles.
    2) Female Argonauta nodosa taking shelter inside the eggcase it created.
    3) Female Argonauta argo inside eggcase with eggs.
    4) Eggcase/shell of female Argonauta nodosa.
    5) Eggcase of Argonauta hians

  • Having explained the relationship between Argonauts and Nautiluses, let us now see whether Argonauts can produce pearls like Nautiluses. The one and only Argonaut pearl believed to have been discovered inside the eggcase/shell of Argonaut hians also known as brown paper nautilus, was discovered in the year 2008, in the South China Sea from Indonesia, as reported by Dr.Tom Stern of the Stanford University, California, in an article published on the website of Societe Des Perles Fines with the following URL
    According to this report the pearl was tested and certified by the GIA in 2008, as an authentic Argonaut pearl. If this report on the Argonaut pearl is true, this pearl is undoubtedly one of the rarest pearls on earth and has great collectors value, as it is the only pearl reported to have been produced by an Octopus, the Argonaut being a species of Octopus.
    Natural pearls are usually defined as hard formations of varying sizes and shapes secreted within the soft tissues, such as the mantle, of living shelled mollusks, as a reaction to an irritant lodging in such tissues, and consisting of a complex scleroprotein called conchiolin and of calcium carbonate in the form of aragonite and or calcite arranged in concentric layers. Argonauts that are considered as a species of Octopus are not shelled mollusks. However, the female Argonauts when mature produce a laterally compressed calcareous egg case commonly referred to as a "shell" in which the eggs are deposited, and later the female also takes refuge inside the so-called "shell." This eggcase is secreted by the tips of the female argonaut's two greatly expanded dorsal tentacles. Since the Argonaut pearl was discovered inside the eggcase of the Brown Paper Nautilus, Argonaut hians, the pearl was undoubtedly produced by the female Argonaut. It is not known in which tissues of the Argonaut the pearl was developed, and whether the secretion of the pearl began, before or after the fertilization of the female and the laying of eggs in the eggcase. It is also not known whether the dorsal tentacles that secreted the eggcase had a role to play in the secretion of this rare spherical argonaut pearl. If it was so, the pearl undoubtedly would have the same composition as the eggcase, and would be made of conchiolin and calcite, and not aragonite as in most other shells. The pearl would then be a non-nacreous pearl, and the appearance of the pearl without the luster and iridescence of nacreous pearls no doubt confirms it. Hence the pearl could have been developed externally like the eggcase being secreted by the dorsal tentacles, or secreted internally inside a tissue like the mantle like any other pearl.
    The CIBJO definition of natural pearl is as follows :-
    natural pearl formations secreted in the interior of molluscs without human intervention. They are composed of a complex scleroprotein named conchiolin (5.47) and of calcium carbonate in the form of aragonite and or calcite arranged in concentric layers. Natural pearls may be nacreous (5.131) or non-nacreous. (5.138). See also 5.146.
    The definition does not mention shelled mollusks. Hence the extremely rare Argonaut pearls, whose origin are not certain whether from shelled or non-shelled mollusks can also fit in to this broad definition of pearls.
    The following thumbnail is that of the Argonaut pearl and the shell of brown paper nautilus in which it was found :-

  • Thanks for sharing your experience of handling a rare Nautilus pearl with our members. Your description of the pearl, such as its white color, translucent nature and porcelain-like appearance, all coincide with previously reported facts about these pearls.
    The 7 Nautilus pearls depicted in Thomas Hochstrasser's website - have the following sizes :-
    The four spherical pearls have diameters of 22.7 mm, 13.6 mm, 9.5 mm and 7.9 mm.
    The button-shaped pearl has a diameter of 17.5 mm, which I presume is the longest diameter.
    The baroque pearl has a diameter of 15.4 mm, which obviously is the longest diameter.
    The cucumber-shaped pearl has a length of 41.3 mm.
    The egg-shaped or oval-shaped Nautilus pearl, which you have described, has a long and short diameter of approximately 8 mm and 6 mm respectively. This is comparable in size to the two smaller spherical pearls, with diameters of 9.5 mm and 7.9 mm.

  • Hi!, I´m new in the forum, I´ve found it very interesting, thank you all!
    I was reading about the Nautilus pearls.
    My mother owns an object, I think it is a "Nautilus shell´s body" with a silver ornament around it.
    It has like a little door in the front, made by a jeweler, when you open it it is the pearl inside.
    Also in the front of the little door (despite the photo is very bad) you can see another little drop pearl hanging there.
    The silver has some french hallmaks on it.
    The pity was that her maid threw it to the floor while cleaning, and the Nautilus shell got broken on a side.
    Is it possible it is a Nautilus pearl??
    Thanks for you help!

  • Hello "tentate",

    Welcome to our forums!!!!

    We will take a closer look at the photos and answer your post within 24 hours.

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    Thanks in advance

  • Hello Tentate,
    I have studied the images you uploaded relevant to the question you have raised, after enlarging the photos using XnView. As you have suggested the object appears to be a portion of a Nautilus Shell. The two halves of the shell after opening the object, reveal the iridescent inner layer of the Nautilus shell. However, the pearl inside is definitely not a Nautilus Pearl. After enlargement using XnView, the pearl appears to be a creamy-orange Melo melo pearl produced by the Gastropod Mollusk, the Melo melo sea snail. The shimmering effect known as "flame stucture" a type of chatoyancy, is clearly visible in the enlarged image of the pearl. Most of the rare Nautilus pearls known are pure white in color, and rarely have a pinkish overtone.
    The drop-shaped white pearl hanging inside appears to be a normal, saltwater, nacreous pearl.
    The views expressed here are my own personal opinion, based on the images you have forwarded to us.
    However, we would try to obtain a second opinion from an expert dealing with pearls, either confirming or rejecting the above views.
    The enlarged images using XnView are also included here for examination by anyone interested.