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Pearl Analysis and Differentiation Techniques: A Comprehensive Guide

Explore pearl formation, types, DNA analysis, and methods for differentiation including x-ray radiography and tomography. Learn to distinguish between natural, cultured, and imitated pearls.

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Pearl Analysis and Differentiation Techniques: A Comprehensive Guide

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  1. Pearls An introduction to pearl formation, types and methods for analysis and differentiation Maria Reichenbach, DénesTary

  2. Overview Maria Reichenbach, DénesTary – Pearls • Introduction to pearls • "Household methods" • Methods of visualization • X-ray radiography (2D) • X-ray tomography (3D) • Neutron imaging • X-ray luminescence – salt- vs. freshwater pearls • Origin of a pearl • DNA analysis • Fluorescence • Age of pearl: Radiocarbon analysis

  3. The givenproblem https://i2.wp.com/deleusejewelers.com/wp-content/uploads/2010/08/IMG_00011.jpg?fit=492%2C360 Maria Reichenbach, DénesTary – Pearls 3 Pearl pendant as heritage Not mentioned in will Value?

  4. Whatis a pearl? Hänni, H.A., 2012. Natural pearls and cultured pearls: a basic concept and its variations. The Australian Gemmologist, 24(11), pp.256-266. Maria Reichenbach, DénesTary – Pearls 4 Biological process in bivalves Accidental Reaction against irritant (tiny organism, organic substance)

  5. Typesofpearls • Cultured • Nacre • Withorwithoutbead • Imitated • Plastic, glass https://sc02.alicdn.com/kf/HTB1CLemJVXXXXX9aXXXq6xXFXXXN/NATURAL-PEARLS-OF-PINCTADA-MAXIMA-CULTURED-PEARLS.jpg_350x350.jpg https://i.etsystatic.com/9797693/d/il/987da8/1299888772/il_340x270.1299888772_hd26.jpg?version=0 https://5.imimg.com/data5/LV/NT/MY-38792203/plastic-white-pearl-500x500.jpg Maria Reichenbach, DénesTary – Pearls 5 • Natural • Nacre • Withoutbead

  6. "Housholdmethods" forpearlanalysis • Texture • rub pearl against your teeth or each other. Nacre is sandy, imitates are smooth • Shape • imitates are perfectly spherical, natural pearls are not • Weight • Imitates are not made of nacre so they have the wrong density Maria Reichenbach, DénesTary – Pearls 6 • Temperature • nacre is cold to the touch and warms up with skin contact, but imitates have room temperature

  7. X-Ray radiography Collimator Scintillator Optional filter(s) X-ray source Detector (CCD) Sample Hänni, H.A., 2012. Natural pearls and cultured pearls: a basic concept and its variations. The Australian Gemmologist, 24(11), pp.256-266. Maria Reichenbach, DénesTary – Pearls 7 Project a picture (2D) of the inside structure

  8. X-Ray radiography Meyer, J.B., Cartier, L.E., Pinto-Figueroa, E.A., Krzemnicki, M.S., Hänni, H.A. and McDonald, B.A., 2013. DNA fingerprinting of pearls to determine their origins. PloS one, 8(10), p.e75606 Maria Reichenbach, DénesTary – Pearls 8 • Revelation ofgrowthstructures • Known, individual development • Bead? cultured • Nobead and freshwaterusuallycultured

  9. X-Ray radiography Krzemnicki, M.S., Friess, S.D., Chalus, P., Hänni, H.A. and Karampelas, S., 2010. X-Ray Computed Microtomography: Distinguishing Natural Pearls from Beaded and Non-Beaded Cultured Pearls. Gems & Gemology, 46(2), 128-134. Hänni, H.A., 2012. Natural pearls and cultured pearls: a basic concept and its variations. The Australian Gemmologist, 24(11), pp.256-266. Maria Reichenbach, DénesTary – Pearls 9

  10. X-Ray tomography Collimator Scintillator Optional filter(s) Computer X-ray source Detector (CCD) Sample Maria Reichenbach, DénesTary – Pearls 10 Almostidenticalto x-rayradiography, but 3D More detailwithmicrotomography Betterviewanglesaccessible

  11. X-Ray tomography Krzemnicki, M.S., Friess, S.D., Chalus, P., Hänni, H.A. and Karampelas, S., 2010. X-Ray Computed Microtomography: Distinguishing Natural Pearls from Beaded and Non-Beaded Cultured Pearls. Gems & Gemology, 46(2), 128-134. Maria Reichenbach, DénesTary – Pearls 11 Identifying a non-beadedculturedpearl

  12. Neutron imaging Neutron tomography X-raymicro-tomography Mannes, D., Hanser, C., Krzemnicki, M., Harti, R.P., Jerjen, I. and Lehmann, E., 2017. Gemmological investigations on pearls and emeralds using neutron imaging. Physics Procedia, 88, pp.134-139. Maria Reichenbach, DénesTary – Pearls 12 Expensive, rarelyused Results with comparable image quality Different contrast, highlighting regions containing organic material (hydrogen containing) Such regions are hard to distinguish from voids using X-ray tomography  complementary measurement

  13. Salt- orfreshwaterpearls?X-rayluminescence Collimator Optional filter(s) X-ray source Sample Maria Reichenbach, DénesTary – Pearls 13 Luminescence is the spontaneous emission of light not caused by heat Apparatus Conventional X-raycabinet Lead glasswindowtoobservetheluminescence

  14. Salt- or freshwater pearls?X-ray luminescence Hänni, H.A., Kiefert, L., Giese, P., 2005. X-ray luminescence, a useful test in pearl testing Maria Reichenbach, DénesTary – Pearls 14 Fresh-water pearls produce luminescence under X-rays Salt-water pearls do not Fresh-water nacre contains traces of manganese

  15. Origin of a pearl: DNA sequencing • 92% CaCO3: aragonite, calcite, vaterite • 4% organic matter: conchiolin and porphirins contains different types of proteins, makes the colour • 4% water • DNA in organic part between layers • Works for coloured and "white" pearls  Negatively charged DNA molecules have high affinity for the Ca2+- ions of CaCO3, which might enhance the conservation of DNA in biogenic gems such as pearls. Meyer, J.B., Cartier, L.E., Pinto-Figueroa, E.A., Krzemnicki, M.S., Hänni, H.A. and McDonald, B.A., 2013. DNA fingerprinting of pearls to determine their origins. PloS one, 8(10), p.e75606 Maria Reichenbach, DénesTary – Pearls 15

  16. Origin of a pearl: DNA sequencing sample preparation • Minimally invasive (10-20 mg) Iftherealreadyis a hole • Powderissuspended in 1000-2000 µL EDTA (0.5 M at pH 8) • Vortexing (thoroughmixing) • Incubateovernight in waterbath at 56°C  Dissolvingof CaCO3requiresharshconditions Meyer, J.B., Cartier, L.E., Pinto-Figueroa, E.A., Krzemnicki, M.S., Hänni, H.A. and McDonald, B.A., 2013. DNA fingerprinting of pearls to determine their origins. PloS one, 8(10), p.e75606 Maria Reichenbach, DénesTary – Pearls 16

  17. Origin of a pearl: DNA sequencing:RFLP - restriction fragment length polymorphismus Meyer, J.B., Cartier, L.E., Pinto-Figueroa, E.A., Krzemnicki, M.S., Hänni, H.A. and McDonald, B.A., 2013. DNA fingerprinting of pearls to determine their origins. PloS one, 8(10), p.e75606 Maria Reichenbach, DénesTary – Pearls 17 DNA is cut by restriction enzymes Fragments are ordered by length using gel-electrophoresis  DNA samples are compared with each other

  18. Origin of a pearl: provenance from Arabian Gulf? http://species-identification.org/species.php?species_group=caribbean_diving_guide&id=417 Maria Reichenbach, DénesTary – Pearls 18 Pinctada radiata is typical for Arabian Gulf Typically oval pearl shape  Compare gained DNA with reference

  19. Origin of a pearl: Laser induced fluorescence – apparatus MyeongJin Ju et al: Multimodal analysis of pearls and pearl treatments by using optical coherence tomography and fluorescence spectroscopy ; OSA, 2011, Vol. 19, No. 7 Maria Reichenbach, DénesTary – Pearls 19

  20. Origin of a pearl: Laser induced fluorescence – used pearls MyeongJin Ju et al: Multimodal analysis of pearls and pearl treatments by using optical coherence tomography and fluorescence spectroscopy ; OSA, 2011, Vol. 19, No. 7 Maria Reichenbach, DénesTary – Pearls 20

  21. Origin of a pearl: Laser induced fluorescence – Time integrated fluorescence spectra MyeongJin Ju et al: Multimodal analysis of pearls and pearl treatments by using optical coherence tomography and fluorescence spectroscopy ; OSA, 2011, Vol. 19, No. 7 Maria Reichenbach, DénesTary – Pearls 21 Akoya South Sea Tahitian Fresh-water (527 nm) (548 nm) (620, 652 nm) (602 nm)

  22. Origin of a pearl: Laser induced fluorescence –Time integrated fluorescence spectra MyeongJin Ju et al: Multimodal analysis of pearls and pearl treatments by using optical coherence tomography and fluorescence spectroscopy ; OSA, 2011, Vol. 19, No. 7 Maria Reichenbach, DénesTary – Pearls 22 South Sea Black Tahitian White Tahitian • Colour ofwhite Tahitian and south sea can not be distinguished by eye but with fluorescence

  23. Origin of a pearl: Laser induced fluorescence –Time integrated fluorescence spectra MyeongJin Ju et al: Multimodal analysis of pearls and pearl treatments by using optical coherence tomography and fluorescence spectroscopy ; OSA, 2011, Vol. 19, No. 7 Maria Reichenbach, DénesTary – Pearls 23 Wavelengths do not overlap with each other Nacre property of a pearl highly depends on the place where the mother oyster was grown

  24. Origin of a pearl: Laser induced fluorescence – decay rates MyeongJin Ju et al: Multimodal analysis of pearls and pearl treatments by using optical coherence tomography and fluorescence spectroscopy ; OSA, 2011, Vol. 19, No. 7 Maria Reichenbach, DénesTary – Pearls 24 Measure for 60 s with 1 s inbetween Cooler conditions cause Akoya pearls to develop their nacre layer more slowly but with more compact crystal structure Affects optical properties and the decay rate of fluorescence

  25. Age of a pearl Krzemnicki, M.S. and Hajdas, I., 2013. Age determination of pearls: A new approach for pearl testing and identification. Radiocarbon, 55(3), pp.1801-1809 Maria Reichenbach, DénesTary – Pearls 25 • Radio carbon dating • Issues: • Sample  invasive(?) • Global 14C distribution • System not always closed • Good method for known pearls, difficult otherwise

  26. Summary & conclusions determinationofmothermollusk origin Maria Reichenbach, DénesTary – Pearls 26 • Methods foranalysis • Visualizationgrowthstructure origin • X-rayradiography/(micro)tomography • Neutron tomography • X-rayluminescencesalt- orfreshwaterdifferentiation • Laser inducedfluorescence • DNA sequencing • Radiocarbondatingagehistoricalconclusions • Trainedeye & knowledgeofpearlsisneeded • Growingdifficultiesforthefield due to well-craftedbeadlesspearls • Impossible totellculturedfromnatural in thefuturevisually?  Laser inducedfluorescence, DNA sequencing & radiocarbondatingwinrelevance

  27. Questions Maria Reichenbach, DénesTary – Pearls

  28. Gemstones Maria Reichenbach, DénesTary – Pearls 28 • What are the differences between testing a coloured gemstone from pearls? • Translucency allows spectroscopic methods • (Crystal) structure can be analysed • Element compositions vary: elemental analysis • different problem, different strategies • One mentioned parallel strategy: • Neutron tomography to identify enclosed organic matters

  29. Reference List Maria Reichenbach, Dénes Tary – Pearls Hänni, H.A., Kiefert, L., Giese, P., 2005. X-ray luminescence, a useful test in pearl testing Hänni, H.A., 2012. Natural pearls and cultured pearls: a basic concept and its variations. The Australian Gemmologist, 24(11), pp.256-266. Krzemnicki, M.S., Friess, S.D., Chalus, P., Hänni, H.A. and Karampelas, S., 2010. X-Ray Computed Microtomography: Distinguishing Natural Pearls from Beaded and Non-Beaded Cultured Pearls. Gems & Gemology, 46(2), 128-134. Krzemnicki, M.S. and Hajdas, I., 2013. Age determination of pearls: A new approach for pearl testing and identification. Radiocarbon, 55(3), pp.1801-1809 Mannes, D., Hanser, C., Krzemnicki, M., Harti, R.P., Jerjen, I. and Lehmann, E., 2017. Gemmological investigations on pearls and emeralds using neutron imaging. Physics Procedia, 88, pp.134-139. Meyer, J.B., Cartier, L.E., Pinto-Figueroa, E.A., Krzemnicki, M.S., Hänni, H.A. and McDonald, B.A., 2013. DNA fingerprinting of pearls to determine their origins. PloS one, 8(10), p.e75606 MyeongJin Ju et al: Multimodal analysis of pearls and pearl treatments by using optical coherence tomography and fluorescence spectroscopy ; OSA, 2011, Vol. 19, No. 7

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