32th IGC Conference, July 2011
Interlaken
Tokki Pearls:
Additional cultured pearls formed during pearl cultivation: External and internal structures
M.S. Krzemnicki1, Müller2, H.A. Hänni3, H-P. Gut4, M. Düggelin5
1Swiss Gemmological Institute SSEF, Basel, Switzerland, 2Hinata Trading Ltd., Kobe, Japan 3GemExpert, Switzerland 4Gloor Instruments, Uster, Switzerland 5Centre for Microscopy, University Basel, Switzerland
“Tokki” is a Japanese term Tokki pearl to describe small „bumps“ (or additional cultured pearls) attached to a larger beaded cultured pearl.
© Swiss Gemmological Institute SSEF
1 Tokki pearl
We can distinguish three types of Tokki pearls:
Type A Type B Type C with an irregular cavity with an irregular cavity with a small additional connected to the bead of („moustache“) cultured pearl the larger cultured pearl surrounded by nacre
© Swiss Gemmological Institute SSEF
Tokki pearl type A
X-ray computed microtomography (coronal sections): Tokki mxt 14b
© Swiss Gemmological Institute SSEF
2 Models of Tokki pearl formation
Tokki Type A: First generation
mantle epithel cavity nacre bead
grafting epithelium “bulging“ nacre deposition Tokki pearl type A
© Swiss Gemmological Institute SSEF
Models of Tokki pearl formation
Tokki Type A: Second generation
bead for 2nd beaded CP generation CP cavity due to incision wound
incision
Tokki pearl first harvest nacre deposition type A
© Swiss Gemmological Institute SSEF
3 Tokki pearl type B
Tokki No. 3
SEM micrograph
© Swiss Gemmological Institute SSEF
Tokki pearl type B
organic rich matter
nacre Calcium carbonate aggregates („globuli“)
4 nacre Tokki 24 Calcium organic rich matter carbonate aggregate
organic rich matter due to a second hemorrhage into the pearl sac
nacre
Tokki pearl type B
Transaxial microtomography sections Coronal microtomography sections
Tokki No. 4 Tokki No. 7
© Swiss Gemmological Institute SSEF
5 Models of Tokki pearl formation
Tokki Type B: First generation
Small „folding“ „moustache“ Two tissues tissue become one piece
formation of docking of independent beadless CP tissue „wrapping“ Tokki pearl grafting beadless CP on beaded CP and nacre cover type B
© Swiss Gemmological Institute SSEF
Tokki pearl type C
© Swiss Gemmological Institute SSEF
6 Tokki pearl type C
nacre Tokki No. 19
Loose ring structures (rich in organic matter) Large drying fissures
Whitish layered CaCO3 „globuli“ interlayed in conchioline
© www.homoeopathie-allenstein.de
7 organic-rich layer
nacre
Tokki No. 13b
Large core with fine-porous and dense columnar intergrowth of
CaCO3
Tokki pearl type C
Tokki No. 10 transaxial sections
© Swiss Gemmological Institute SSEF
8 Tokki pearl type C
Tokki No. 15, coronal sections © Swiss Gemmological Institute SSEF
drying fissures
latest nacre layer
Tokki No. 22 loose nacre layers
9 Soap bubbles....
Models of Tokki pearl formation
First generation Tokki Type C:
CaCO conchioline-rich tiny 3 „spot“ layers Two tissues tissue become one piece
formation of docking of independent additional CP tissue „wrapping“ Tokki pearl grafting additional CP on beaded CP and nacre cover type C
© Swiss Gemmological Institute SSEF
10 Pertinence for pearl testing
Additional cultured pearl formation: First generation
CaCO Additional tiny 3 „spot“ cultured pearl tissue piece
formation of independent additional CP grafting additional CP remains loose
© Swiss Gemmological Institute SSEF
Pertinence for pearl testing
Detection of additional cultured pearls !
mxt61_20
© Swiss Gemmological Institute SSEF
11 Pertinence for pearl testing
Natural or cultured pearls ?
Photo & Radiography © GPTL Bahrain
Pertinence for pearl testing
Loose ring structures (conchioline-rich) whitish „globuli“
former „docking“ feature of Tokki pearl to larger beaded CP pearl Photo & Radiography © GPTL Bahrain
12 Pertinence for pearl testing
Additional cultured pearls:
whitish globuli
mxt61_20
White CaCO3 central spot
© PhotoSwiss &Gemmological Radiography Institute© GPTL BahrainSSEF
Conclusions Tokki pearls are a by-product of pearl cultivation
We distinguish three types of tokki pearls (cultured pearls) depending on their internal structures.
Tokki pearls may fall from the larger cultured pearl during harvesting or even not attach to the cultured pearl at all; thus be present as loose additional cultured pearl!
Tokki pearls (and additional cultured pearls) generally are characterised by loose ring structures, distinct drying fissures, a calcium carbonate central core surrounded by organic-rich layers, and often irregularly distributed small calcium carbonate spheres („globuli“)
Using radiography and microtomography, Tokki pearls and additional cultured pearls can be detected.
© Swiss Gemmological Institute SSEF
13 Thank you for your attention
Acknowledgements: - Andy Müller for the donation of many cultured pearl samples - Sam Buchanan for comments and discussions - Dr. Franz Herzog and Piotr Halicki for many pearl radiographies - Ali Safar and Abeer Al Alawi from the Bahrain Pearl and Gemstone Testing Laboratory for radiographies and fruitful discussions
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