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Annual Conference 2010
Speakers and Workshop Leaders
Dr. Dietmar Schwarz - Research Manager, Gubelin
Laboratory, Switzerland
Emeralds
of the World and the World of Emeralds
A review of emeralds:
What is an emerald and how does emerald form? When is a green beryl an
emerald? Where is emerald found and where are the current market
sources? Is it possible to determine the origin of an emerald?
and
Coloured Gemstones - Mines and markets
Dr
Schwarz will address commercially traded coloured gemstones like
ruby and spinel; gem-producing countries and the regions from which
these stones are recovered and the importance of gemstones to the
local mining communities and the wider market in general
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Dr.
Dietmar Schwarz studied at Johannes Gutenberg University,
Mainz, Germany. He was then a scientific lecturer at the
German Academic Exchange Service (DAAD) and Professor of Mineralogy and
Gemmology at Ouro Preto Federal University, Minas Gerais,
Brazil. Since 1992 he has been employed
at the Gubelin Gem
Laboratory in Lucerne, Switzerland, where he is currently
Research Manager. A
well known and respected gemmologist, he has written
extensively on various aspects of gemmology and mineralogy
for Gems and Gemology as well as all the other widely read
gemmological publications. He is also the author of a book
on emeralds published in 1987. Dietmar has presented in
nearly fifty conferences and over twenty specially arranged
courses/seminars throughout the world. Dietmar is also an
active member of various gemmological committees, such as
the Laboratory Manual Harmonization Committee (LMHC), and is
a regular participant at the International Gemological
Conference.
There
is no doubt that Dr. Schwarz can be considered to be one of
the leading gemmologists in the world today. |
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Maria Alferova
-Mineralogist and Gemmologist, Fersman Museum, Moscow
Fabergé - 'The Lost and Last
Easter Egg'
Fabergé: The “Lost and Last” Easter Egg.
The talk will focus on an item stored among the Fabergé collection donated
to Alexander Fersman in 1920s and later to the Fersman Mineralogical
Museum. The item was recently attributed to Fabergé as being one of the famous Easter
eggs – the last line of the presents to the Royal family.
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Maria
S. Alferova
is a mineralogist and gemmologist (MSc); at present she is a
curator and gem-expert at the Fersman Mineralogical Museum.
Maria was lecturing gemmology at the Moscow State University and
fulfilled extensive museum and gemmological fieldwork in Russia,
Europe and USA. Maria is a member of the Russian gemmological
Society, Society of Mineral Museum Professionals and the
Scottish Gemmological Association. She has an interest in
optical phenomena in gemstones, field gemmology and Scottish
country dancing.
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David Callaghan
Upon Reflection.
An excursion into the
phenomenon of reflection.
Reflection:
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The phenomenon of light, heat or sound being reflected. |
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Serious thought or consideration – a considered idea. |
In his definitive book –
Gem Testing for
Jewellers
– the late Basil Anderson poses the question:
What happens when
light falls on the surface of a gemstone? Some of it is reflected at the surface
of the stone…
However, as all
gemmologists know, this is only part of the story as the greater proportion of
the light enters the gemstone – the phenomenon of refraction. To appreciate a
gemstone’s colour we have to try to “recover” this absorbed light and return as
much as possible to the eye. Having given the subject some ‘serious thought’
- hence the title of David’s talk – he invites debate on which of these two
phenomena is of the greater importance to the observer to enable the beauty of a
gemstone to be revealed.
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David
Callaghan
began his career in the jewellery trade in 1955 when he was
apprenticed to Hancocks & Company. He was appointed a Director
in 1964 and continued to work there throughout his career. He
retired in 1997.
Born in
1938 he was educated at St. Paul’s Cathedral Choir School
(1947-1952) where in his last term he was Head Chorister. He
then became a pupil at Magdalen College School, Oxford
(1952-55). He qualified as an FGA in 1958. He is a Freeman of
the City of London and was ‘clothed with the Livery’ of the
Goldsmiths’ Company in 1983.
NAG
Chairman (1976-78) he was their President (1999-2001). He was
also Chairman of the former Gemmological Association of Great
Britain, now Gem-A, for 14 years (1979-93).
David’s
lecture entitled ‘Upon Reflection’ is a non-taxing,
somewhat oblique, view of the phenomenon of reflection and how
its role in the disturbance of light enables us to see shape and
form clearly. |
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Gwyn Green FGA, DGA
The Identification of Colourless Gems in Jewellery.
The subject will be
tackled from the viewpoint of someone away from home at a car boot sale,
market or auction where the availability of specialist equipment is
minimal.
After the
recognition of diamond, separating it from its look-alikes, what can be
done in order to identify other colourless stones more commonly
encountered in modern and older jewellery?
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Gwyn Green has taught gemmology since qualifying in 1985: as a
diploma correspondence tutor since the inception of the new course in
1986; has held seminars and full courses at home; has organized
practical days for the Midlands Branch for over 25 years; has been a
correspondence tutor for the diamond course for about 10 years and a
gemmology diploma examiner for 5 or 6 years.
Before becoming an examiner she specialized in pre-exam
seminars for Gem-A students. Gwyn taught at the Birmingham Jewellery
School, first preliminary and then diploma gemmology evening classes -
both theory and practical for many years. She inaugurated and wrote the
two year, full time, HND Gemmology course for which she taught the
inaugural group at the Birmingham School of Jewellery. Gwyn has authored
books, articles and talks, both for gemmology groups and lay people,
over the years. As past Chairman of the Midlands Branch of the Gem-A,
for ten years, Gwyn remains a key figure in planning gemmology seminars
for the Midlands area and organising various other functions. |
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Alan Hodgkinson
- President of the Scottish Gemmological Association
Visual Optics
Alan will retrace
the development of this Gem-to-the-Eye method of assessing a gemstone's
optical properties. The individual contribution of refractive index,
birefringence, absorption (in certain cases) and dispersion, come
together collectively to form on the eye's retina. It is there that the
gemmological mind i.e. gemmologist or student, can interpret the colours
and patterns, and make certain diagnostic predictions from their
gemmological knowledge. In certain situations, the identity is apparent,
as with diamond, ruby, zircon, certain tourmaline. More generally, the
method allows the elimination of identity as in the illustration which
separates zircon from lithium niobate, and yet they can be all too
easily confused by 10x loupe.
The zircon/lithium
niobate distinction is simply achieved by their contrasting B/D ratio. B
is the birefringence, divided by D, the dispersion.
The B/D ratio of
zircon is ~ 1.5. the B/D ratio of lithium niobate ~ 0.7.
In simple terms, the
doubled primary images of the zircon separate at their widest, while
those of the lithium niobate can never separate, even at their widest
extent of separation.
The concept of a
Visual Optics refractometer will be demonstrated. This works on the
principle of a pinhole or air refractometer i.e. there is no instrument
or contact fluid involved.
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Zircon and Lithium Niobate
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Zircon |
Lithium Niobate |
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Our
Honorary President and well-known international gemmologist and
lecturer, Alan Hodgkinson, has spent the last fifty years
sharing his enthusiasm about gemstones with others. He is known for
his innovative and highly effective practical gem identification
techniques, including ways to see and learn more using traditional
gem testing instrumentation. He is the author of Visual Optics, and
a new book about to be released, Gem Testing Techniques.
Alan
is a Fellow of the Gemmological Association (FGA) With
Distinction, is a Freeman of the Worshipful Company of
Goldsmiths, an Honorary Member of the Canadian Gemmological
Association and a Registered Valuer.
Alan
was honoured to be the first recipient of the Antonio C. Bonanno
Award for Excellence in Gemology in 2000 and was presented with
the award at a gala dinner at the Tucson show in that year. |
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Dr Jack
Ogden - Chief Executive, Gem-A
'Eastern Promise: a history of gem
trade from India and Ceylon'
"For two and
half millennia the gems from India and Ceylon have been prized
imports into Europe. The range of gem materials brough from this
region is truly astounding and includes diamonds, rubies, sapphires,
cats' eyes, tourmalines and pearls. This presentation will trace the
history and growth of this gem trade from the days of Alexander the
Great through medieval contacts up to the East India Company's work
and finally Victorian interest with Prince Albert and the Great
Exhibition."
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Dr Jack Ogden has been the Chief
Executive of the Gemmological Association of Great Britain
(Gem-A) since 2004. Jack is the fourth generation of a
well-known British jewellery business, but after gaining his
Gem-A Diploma (‘FGA’) with distinction in 1971 he entered the
consulting field, working with museums, auction houses, dealers
and collectors worldwide advising within his specialist field of
the history of jewellery materials and technology, with a
special focus on problems of authenticity. His Doctoral Thesis
(Durham University) dealt with the jewellery industry in
Hellenistic and Roman Egypt. He has written and lectured widely
on ancient and historic jewellery and taught courses at The J.
Paul Getty Museum, Smithsonian Institution, Institute of Fine
Arts (NY) and Institute of Archaeology (London). He is vice
chairman of the UK Government Treasure Valuation Committee and
an elected Fellow of the Society of Antiquaries of London.
Between 1995 and 2000 he was Secretary General to CIBJO (The
World Jewellery Confederation).
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Dr. Don Hoover, FGA
Magnetic
Susceptibility of Gemstones
Don will introduce the concept of magnetic susceptibility of
gemstones and how it can be used, in conjunction with other physical and optical
properties, to discriminate gemstone species with particular emphasis on gem
garnets.
The talk will be followed by a practical demonstration of the technique using specially
modified microscopes and rare earth magnets with the opportunity for hands-on
measurement.
(This talk was cancelled due to air
traffic disruption caused by volcanic ash)
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Dr. Don Hoover graduated in electrical
engineering, and then studied for a doctorate in
geophysics. He was a research geophysicist with the U.
S. Geological Survey in Denver, Colorado and has
published over 100 professional papers and reports
related to exploration geophysics and mineral deposits.
Following his retirement, Don has spent considerable
time on researching into gemstones and their
properties.Don is author of one
of the well known Butterworth-Heinemann series of
monographs, 'Topaz', on gem topaz.
He has published papers on
fluorescence in gemstones, use of cross-filters and seminal
papers on magnetic susceptibility as a means of discriminating
gemstones and also as a means of identifying garnets |
Workshop Leaders
Vanessa Paterson GG, FGA
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Vanessa Paterson, GG, FGA has been in the
jewellery industry for over 28 years She has been involved in
many aspects of the trade, from retailing to valuing jewellery
as well as spending her free hours researching into gemstones.
She has travelled all over the world in her pursuit of her
passion for gemmology, including visiting a pearl fisher in New
Zealand (the only pearl fisher to dive for wild abalone for its
meat and pearls).
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Brian Jackson FGA,DGA
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Brian Jackson
is Principal Curator of Mineralogy at the National Museums of
Scotland with specific
responsibility for strategic development of the mineral and
economic mineral collections and curatorial policies relating to
these including partnerships with other institutions.
Research Interest/Expertise: All minerals and gems and the
application of FTIR (a type of chemical analysis) to identify
and study them, Strontian Lead Mines, Scottish gold and low
grade metamorphism as an alternative new approach to
mineral-forming processes, pegmatite minerals and gem feldspar.
The author of chapters of
Websters: Gems on Garnets and Feldspars and many papers on gems
and gemmology. Brian is also Chairman of the Scottish
Gemmological Association and a council member of the Gem-A |
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The
Scottish Gemmological Association
