The ‘Sleeping Lion’ Baroque Pearl: An Update

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DOI: 10.15506/JoG.2014.34.3.248
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The Sleeping Lion is one of the largest-known nacreous pearls and has an interesting history. Newly discovered early references indicate that soon after the pearl was sold in Amsterdam in 1778, it was offered for sale in St. Petersburg in 1779. The pearl was recently removed from its setting, allowing its weight to finally be determined at 2,373 grains (593 ct or 118.65 grams). High-resolution X-ray micro-CT scanning revealed the inner structure of the pearl in much greater detail than could be seen during a previous study, and together with Raman spectroscopy, confirmed that the Sleeping Lion is a natural blister pearl. As properties presented in a previous study indicate that this pearl has a freshwater origin, it can be reaffirmed that this is the largest natural freshwater blister pearl documented to date.
248 The Journal of Gemmology, 34(3), 2014
Gemmological Brief
The Sleeping Lion is one of the largest-known nacreous pearls and has an
interesting history. Newly discovered early references indicate that soon
after the pearl was sold in Amsterdam in 1778, it was offered for sale in St.
Petersburg in 1779. The pearl was recently removed from its setting, allowing
its weight to nally be determined at 2,373 grains (593 ct or 118.65 grams).
High-resolution X-ray micro-CT scanning revealed the inner structure of the
pearl in much greater detail than could be seen during a previous study,
and together with Raman spectroscopy, conrmed that the Sleeping Lion is
a natural blister pearl. As properties presented in a previous study indicate
that this pearl has a freshwater origin, it can be reafrmed that this is the
largest natural freshwater blister pearl documented to date.
The Journal of Gemmology, 34(3), 2014, pp. 248–253,
© 2014 The Gemmological Association of Great Britain
The ‘Sleeping Lion’ Baroque Pearl:
An Update
J. C. (Hanco) Zwaan, Dirk M. van der Marel and Herman A. Dommisse
Five years ago, two of the present authors
described the properties and history of one
of the largest-known nacreous pearls (Zwaan
and Dommisse, 2009; Figure 1). At the time
we had to estimate the weight of the pearl
because it was tightly mounted on a gold rod
that was used to set the pearl in the centre of
a stylized Lotus bud (Figure 1, inset). However,
this rod was removed after the owner decided
to show the pearl loose, in order to showcase
its ‘sleeping lion’ appearance when presented on
its original display box (described in Zwaan and
Dommisse, 2009; see Figure 2). This gave us the
opportunity to weigh the loose pearl, and also to
examine it with high-resolution X-ray computed
microtomography (micro-CT). This short note
gives additional historical information and also
updates the properties of this remarkable pearl.
From historical accounts, Zwaan and Dommisse
(2009) reported that the pearl was sold in
Amsterdam in 1778, as “a large pearl, of 578
carats, visualizing a sleeping lion…”. After it was
sold, the pearl’s history was unknown until 1865,
when the second-known owner from Poland
appeared, shortly before the return of the pearl
to Amsterdam around 1868.
New information on the history of the pearl
was found in an old recipe book for edible
molluscs (Lovell, 1867), and kindly brought to
our attention by Dr Jack Ogden. It reveals that the
pearl probably left Amsterdam shortly after it was
The 'Sleeping Lion' Pearl
Gemmological Brief
auctioned in 1778, to be sold in St. Petersburg,
Russia, the following year: “In 1779 a pearl, which
from its shape was called the Sleeping Lion, was
offered for sale at St. Petersburg by a Dutchman;
it weighed 578 carats, and was bought in India for
£4500” (Lovell, 1867, p. 60). Further, Dr Ogden
indicated that this information was evidently
taken from Nicholson (1808, unpaginated, from
the section ‘Pearls’): “A pearl, called from its
gure the sleeping lion, that weighed 578 carats,
was offered for sale at Petersburg in 1779 by a
Dutchman. On one side, which was attish, it
was beautifully striped. It was bought in India
for 4500l.” The young Nicholson (1753–1815), a
scientist and inventor, arrived in Amsterdam in
the summer of 1777 as a sales representative for
the English pottery rm of Wedgwood & Bentley
(Lamp, 2004). For three years he worked in the
old town centre, a few steps away from the Munt
tower where the Sleeping Lion Pearl would be
auctioned on 26 August 1778. His quote strongly
suggests that he had seen the pearl and had
Figure 1: The Sleeping Lion Pearl, which measures approximately 70 × 43 × 39 mm, has been removed from its former setting
in the centre of a stylized lotus bud (lower right, photo © Amsterdam Pearl Society). It is now displayed as a loose pearl, as
drawn in 1778 (upper right); photo by J. C. Zwaan.
Figure 2: The Sleeping Lion Pearl is displayed on the gilded
copper box (approximately 74 × 54 × 47 mm) that was
originally manufactured for it. Photo by Tom Haartsen,
© Amsterdam Pearl Society.
Gemmological Brief
250 The Journal of Gemmology, 34(3), 2014
Figure 3: A 3D model of the Sleeping Lion Pearl (a) was reconstructed from X-ray micro-CT scans. Concentric layering is seen in
the ve scans shown here that were taken along the length of the pearl, from top to bottom (b–f).
The 'Sleeping Lion' Pearl
Gemmological Brief
carefully observed it himself (the pearl indeed
has a rather at ‘striped’ reverse side; compare
with Figure 4 in Zwaan and Dommisse, 2009).
Otherwise he must have taken these observations
from somewhere else, but then there would have
to be another (slightly older, Dutch?) reference
which, to date, has not been found.
This new piece of information, stating that the
pearl was bought in India, does not contradict a
Far East (or Chinese) origin, as postulated earlier;
it also indicates that the pearl probably went to
Russia twice, as the previous Dutch owner Louk
van Kooten stated that his grandfather Louis van
Kooten took the pearl to Fabergé in St. Petersburg,
sometime between 1910 and 1914 (Zwaan and
Dommisse, 2009).
The weight of the pearl immediately after the
removal of the mounting rod was 593.29 ct
(2373.16 grains). Subsequently, the small and
narrow drill hole was lled with a mixture of
mother-of-pearl grit and glue. The weight of the
pearl including this lling is 593.43 ct (2373.72
grains). Thus we have conrmed that the actual
weight of the pearl is 2373 grains (118.65 grams),
which is 0.6 grams lower than the weight
estimated by Zwaan and Dommisse (2009).
Comparing this weight with the 578 ct
mentioned by Nicholson (1808) and Lovell (1867),
the carat weight used at the time (before the
standardization of the metric carat in the early 20th
century) must have been around 0.2053 grams,
which is exactly the value of the London carat and
close to the value of the Amsterdam carat of 0.2057
grams at the end of the 19th century, according to
the values given by Lenzen (1970).
Inner Structure and Composition
With the pearl unmounted, we also had the
opportunity to study its internal structure with
high-resolution X-ray micro-CT scanning, without
having to deal with interference problems due
to the presence of a metal rod. A Skyscan 1172
micro-CT scanner was used for this purpose.
The operating conditions were set at 100 kV and
100 µA, using both Al- and Cu-foil lters and an
exposure time of 5,500 milliseconds for each
image. Due to its large size, the pearl was divided
into ve parts that were separately scanned, with
the camera offset turned on. For each scan, the
pearl was rotated 180° in steps of 0.30°. For
each position, three frames were averaged. The
ve separate scans were stitched together, and
after reconstruction a total of 5,325 images were
processed. The camera pixel size was xed at
8.70 µm; after reconstruction, the image pixel
size was 13.17 µm. From the reconstructed three-
dimensional (3D) model of the pearl, a video was
made to show the internal structures along almost
the entire length of the pearl, and then going into
the pearl from its reverse side (available in an
online data depository on The Journal’s website).
The high-resolution X-ray micro-CT scans
(Figure 3) provide much more detail than the
original CT scans (compare w ith Figure 6 of
Zwaan and Dommisse, 2009). Although the shape
of the pearl is highly irregular, it shows remarkably
consistent concentric layering—typical of natural
pearls—that is oriented perpendicular to the long
axis of the pearl. The scans also conrm that the
pearl is solid throughout, without any substantial
hollow cavities. Where cavities are present, they
are small and very shallow or thin. When the
pearl was viewed from its reverse side (Figure 4;
compare with Figure 4 of Zwaan and Dommisse,
2009), parallel growth lines were observed on
and near the surface, indicating that this side of
the pearl was attached to the shell of the host
mollusc. These properties indeed conrm that
this is a natural blister pearl.
Raman spectroscopy, using a Thermo DXR
Raman microscope with 532 nm laser excitation,
was employed to analyse ve randomly chosen
spots at and slightly underneath the surface of
the pearl. The Raman spectra revealed that the
white surface consisted of aragonite, with main
bands at 1085, 706 and 701 cm–1. The strongest
band, at 1085 cm–1, derives from the symmetric
stretching mode (ν1) of the carbonate ion; the
doublet at 706 and 701 cm–1 corresponds to in-
plane bending (ν4) of the carbonate ion, which
is in contrast to the single band at ~711 cm–1
found in Raman spectra of calcite (compare, e.g.,
Urmos et al., 1991; Wehrmeister et al., 2010).
Therefore, Raman analysis conrms the nacreous
nature of this pearl, as already concluded by
Zwaan and Dommisse (2009) on the basis of its
Gemmological Brief
252 The Journal of Gemmology, 34(3), 2014
Figure 4: Viewed from its reverse side, the Sleeping Lion Pearl is shown as a 3D model (a) and also in slices (b–d) that
reveal parallel growth lines which are oriented roughly parallel to the orientation of the pearl’s attachment with the shell of
its host mollusc.
The 'Sleeping Lion' Pearl
Gemmological Brief
The Authors
Dr J. C. (Hanco) Zwaan and
Dirk M. van der Marel
Netherlands Gemmological Laboratory/
Naturalis, P.O. Box 9517, Leiden,
The Netherlands
Herman A. Dommisse
Amsterdam Pearl Society, Amsterdam,
The Netherlands; owner of the Sleeping Lion
Dr Jack Ogden is thanked for pointing us to
the historical references mentioned.
optical features. A small, slightly brownish area
near the borehole did not reveal bands related
to a particular pigment; the Raman spectrum
was inuenced by relatively strong uorescence
instead. It is possible that this slight coloration
formed during the drilling of the borehole.
New evidence shows that soon after the Sleeping
Lion Pearl was auctioned in Amsterdam in 1778, it
was then offered for sale in St. Petersburg in 1779.
The measured weight of the pearl is 2,373
grains; it is therefore conrmed to be one of the
largest-known nacreous pearls, slightly less in
weight than the Pearl of Asia (2,420 grains) and
slightly greater than the Arco Valley Pearl (2,300
grains; cf. Table II of Zwaan and Dommisse, 2009).
High-resolution X-ray micro-CT scanning and
Raman analysis conrmed that this is a naturally
formed nacreous blister pearl without any substantial
hollow cavities.
Lamp P., 2004. Drie eeuwen Wedgwood en Nederland.
Damon BV, Amsterdam, The Netherlands, 221 pp.
Lenzen G., 1970. The History of Diamond Production
and the Diamond Trade. Transl. by F. Bradley,
Barrie and Jenkins, London, 230 pp.
Lovell M.S., 1867. The Edible Mollusks of Great Britain
and Ireland, with Recipes for Cooking Them. Reeve &
Co., London, 207 pp.,
Nicholson W., 1808. A Dictionary of Practical and
Theoretical Chemistry, with its Application to the
Arts and Manufactures, and to the Explanation of
the Phaenomena of Nature; Including throughout
the Latest Discoveries, and the Present State of
Knowledge on those Subjects. Richard Phillips,
London, 826 pp.,
Urmos J., Sharma S.K. and Mackenzie F.T., 1991.
Characterization of some biogenic carbonates
with Raman spectroscopy. American Mineralogist,
76(3–4), 641–646.
Wehrmeister U., Soldati A.L., Jacob D.E. and Häger T.,
2010. Raman spectroscopy of synthetic, geological
and biological vaterite: A Raman spectroscopic
study. Journal of Raman Spectroscopy, 41, 193–201,
Zwaan J.C. and Dommisse H.A., 2009. A description
and history of one of the largest nacreous pearls in
the world. Journal of Gemmology, 31(5-8), 196–202,
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