Thanks and disclaimer:


Important Note: The author: Vincent Pardieu is an employee of GIA (Gemological Institute of America) Laboratory Bangkok since Dec 2008. Any views expressed on this website - and in particular any views expressed by Vincent Pardieu - are the authors' opinions and do not necessarily reflect the opinions of GIA or GIA Laboratory Bangkok . GIA takes no responsibility and assumes no liability for any content on this website nor is GIA liable for any mistakes or omissions you may encounter. GIA is in particular not screening, editing or monitoring the content on this website and has no possibility to remove, screen or edit any content.


About FieldGemology. org

This website is home for "Shameless Travel Addicted Gemologist" Vincent Pardieu (B.Sc., GGA, G.G.). Vincent is "Supervisor, Field Gemology" at GIA Laboratory Bangkok. He is a gemologist specialized on "origin determination of gemstones".
This is also home for Vincent's regular traveling companions: David Bright, Jean Baptiste Senoble, Richard W. Hughes, Guillaume Soubiraa, Walter Balmer, Michael Rogers, Kham Vannaxay and many others like recently: Philippe Ressigeac, Oliver Segura , Flavie Isatelle and Lou Pierre Bryl.

We are gemologists (gemmologists) sharing a passion for gemstones, gemolology (gemmology), gem people and traveling.

You will find in this website gemological expedition reports and some studies of gemological interest.

Visiting many gem mining areas we saw that people in remote mining and trading areas have difficulties to access to gemological publications. As today the Internet can be accessed in most of these gem mining areas and trading centers, the author started to build this website to give gem people living there the opportunity to see the result of the gemological expeditions they were associated in. It is a way to thanks them for their time and collaboration and to help them to get access to more gemological information.

At the same time the author hope that these expedition reports will please the people from consuming countries interested in gemstones and fascinated by their mysterious origins. Our purpose here is to help people facing difficulties to get quality first hand information about gems and their origins to get the information they need through this website and its links.

With our field expeditions to gemstone mines and gem markets around the world, we intend also here to share our passion for photography, gems and our fascination for the work of the "Gem People" bringing gemstones from the ground to magnificent jewelry.

From the gems external beauty to the intimate beauty of gemstone inclusions, from gem lore to the mines, the people and the landscapes gems origin from, we expect to share with you our passion for gemstone beauty.

We also invite you to join us on some gemological forums we are active in as they are convenient tools to get rapid answers to your questions as they are regularly visited by many other passionate gemologists, jewelers, hobbyists and professionals willing to learn more and share their knowledge about gemstones.


Website Map


Index page: Vincent Pardieu's Blog

About the Author

About me : How did a countryside Frenchman became a "Shameless travel addicted gemologist"? ( Under construction)


Contact the author:


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Fieldgemology Page on facebook

Popular Articles

"Tsavorite, an Untamed Gem" with R.W.Hughes, first published in ICA's InColor (Winter 2008)
"Working the blue seam" The Tanzanite mines of Merelani with R.W.Hughes first published on
"Spinel, the resurection of a Classic" with R.W. Hughes, first published in ICA's InColor (Summer 2008)

Gemological studies

(Apr. 2009) "Sapphires reportedly from Batakundi / Basil area" a preliminary study about unusual sapphires we saw at GIA Laboratory Bangkok
(Mar. 2009) "Rubies from Niassa province, Mozambique" a preliminary study about rubies we saw at GIA Laboratory Bangkok
"Lead glass filled rubies" :
First published on AIGS Lab Website (Feb 2005)

Expedition Reports

Autumn. 2009: GIA Field Expedition FE09: Rubies from Mozambique. (pdf file)

May. 2009: GIA Field Expedition FE08: Melos and their pearls in Vietnam. (pdf file)

Dec. 2008 and Feb-Mar. 2009: GIA Field Expeditions FE01 and FE04: Rubies and sapphires from Pailin, Cambodia. (pdf file)

Aug. 2008: Sapphires and Tsavorite from the south of Madagascar with the AFG (Association francaise de Gemmologie) : Available soon...

Apr. 2008: Expedition to the new Winza ruby deposit in central Tanzania with Jean Baptiste Senoble and the support of the Gubelin Gem Lab

October 2007: Gemological expedition to East Africa (Kenya and Tanzania) with Richard W. Hughes, Mike Rogers, Guillaume Soubiraa, Warne and Monty Chitty and Philippe Bruno:

Summer 2006: Expeditions to Central Asia gem wealth with Guillaume Soubiraa and the support of the AIGS, the ICA and the Gubelin Gem Lab:

Oct. 2005: Colombia by J.B. Senoble

Sep. 2005: Madagascar with Richard W. Hughes and Dana Schorr (Will be available one of these days...)

Summer 2005: Gemological expeditions to South East Asia (Vietnam) South Asia (Sri Lanka) and East Africa (Kenya, Madagascar and Tanzania) with J.B. Senoble and Tanguy Lagache with the support of the AIGS, the ICA and the Gubelin Gem Lab:

- Feb. 2005: A visit to Thailand, Cambodia with the AFG (Association Francaise de Gemmologie) (under construction)

- 2002-2007: Expeditions to Pailin (Cambodia), Chanthaburi Kanchanaburi (Thailand) Houay Xai (Laos) Mogok, Namya (Burma) (under construction)

- 2001: Expeditions to Namya, Hpakant and then Mogok with Ted and Angelo Themelis and Hemi Englisher (under construction)

Find our blogs using the following Keywords:

Find our photos using the following Keywords:

Discover fieldgemology newsletter:
(Currently under "hibernation status"...)

Number 01: Sept 2006
(I know: it was long time ago...)



THANKS for their support
for our field expeditions since 2005:


about gems, gemology, field expeditions, studying gemology, minerals, jade, pearls or jewelry?
We recommend these FORUMS
where the author is contributing:

Do you want to

Here are some recommended institutes where the author studied gemology in Thailand ... and was happy about his investment!

For those willing to go further after their gemological studies: Recommended Advanced Gemological Courses:

To finish here are some BOOKS about gemology
the author have read and appreciated and would like to recommend to people willing to learn more about gemstones, gemology and the places where gemstones are found:




Creative Commons License

The photos and articles on are licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.
Feel free to use the photos and articles with links and credits. No commercial use without permission.
All the best,


On the way to Tsavo:
Prospecting for gems in the bush,

visit at the "Simba" Ruby mine,

Text by
Vincent Pardieu (Gubelin Gem Lab, Lucerne, Switzerland)

Photos by
Vincent Pardieu, and Jean Baptiste Senoble

The 2005 and 2007 expeditions were supported by the Gubelin Gem Lab located in Luzern, Switzerland, as the 2005 expedition was financed by the Gubelin Gem Lab and the AIGS Gemological Laboratory in Bangkok, Thailand and, because at the time of the 2007 expedition the author was working at the Gubelin Gem Lab as a gemologist.

Presentation of the Simba Ruby deposit:

Rubies were told us to have been first reported in the Simba area in 2005. The deposit is magmatic but I prefer to say that the rubies are "basalt related" as it is not clear if the rubies were formed in the magma or where just transported by this magma the later been the more likely I feel that the term "basalt related" is more suitable. Rubies are found on the volcanic crater and its surroundings composed mainly of basalts. They are associated with olivine and colorless zircons.

I visited this area in July 2005 and October 2007. The area is very easy to access, just few hundred meters from Kenya main road linking Mombasa to Nairobi. No real mining was occuring in the area, but some prospection was taking place in 2007 using hand tools. During my nsecond visit in 2007 with Richard W Hughes, Michael Rogers and Guillaume Soubiraa we met a group of Thai field geologists from a Thai university. They were there to study the deposit. The main challenge regarding mining at Simba like in many other places in Kenya is the lack of water. Recently I was informed that a mining right were sold to a Russian group.

Most of the stones from Simba we saw were light pink or red in color, the best stones reminding the stones found in Thailand and Cambodia. They were mostly flat and their size was going from 1 to about 20 carat rough. The stones from Simba looks then more red than their more pinkish counsins from Baringo. At Simba, rubies and pink sapphire are associated with colorless zircons.

The purpose of these expedition to the Simba ruby deposit was to collect data for gemological research purpose regarding origin determination of rubies. Origin determination of gemstones is an important part of the daily work at the Gubelin Gem Lab where the author is an employee. To maintain our capacities at their best level regarding origin determination, it is important to keep our reference stone collection up to date and to collect data at the source.

1) Introduction:

We invite you to follow our winter 2007 fieldtrip to the mergui pearl farms using the potential given by the free software Google Earth. Just download and install the software, then using our links you can get a better idea about the mining areas we visited or those for which information is available in the gemological litterature. We recommend you to select the "terrain" option (down left in the "layer" booklet) in order to enjoy a 3D visit.

Using our Google Earth placemarks, you can now follow our expeditions and explore East Africa downloading the placemarks we prepared.
Just download them clicking on the icon on the left to fly to Kenya and Tanzania

On our way to Tsavo in July 2005 we stopped near Kasala village to see some gemstone mining prospection. Villagers were digging prospection trenches in the bush to collect and study the minerals.

On our way to Tsavo we also stopped to visit to a new ruby mining area located near the Simba village:
The Simba village is located on the main road linking Nairobi to Mombasa. Its main activity is agriculture. The mining area is located around the nearby volcano on which children were keeping goats. One of these young goat keeper was reported to us to have found the first ruby in 2004.

A ruby miner working on a prospection spot near Simba (October 2007).

Prospection mining holes and trenches in Simba area. (October 2007)

A small hand of Simba rubies as those collected by local people after the rains. These basalt related rubies are easy to recognise for the field gemmologist with their corroded/melted smooth surface. The same aspect is found commonly for stones in other basalt related deposits such as Thailand, Cambodia, South Vietnam, China, Australia, Ambondromifehy ( North of Madagascar), Rwanda, and some other parts of Kenya such as Baringo.

Kenyan gem dealer and miner: Kennedy Khamwathi presenting a ruby from the Simba ruby deposit..

Brief gemological properties of Rubies from the Simba area, Kenya:

Color: Pinkish red to purplish red and red
Refractive Index:
1.76 to 1.77
Birefringence: -0.007
Specific Gravity: 3.99
Dichroism: Purplish to Orangy
Optic Sign: Uniaxial Negative
Chealsea Filter: Reddish
SWUV: None to weak red
LWUV: None to faint red
Origin of Color: Cr
Inclusions: Twinning, intersection tubes, crystals with equatorial hexagonal iridescentthin films.

The most distinctive inclusion in Simba rubies are the numerous minute crystals (visible using bright field illumination like in the following photo) associated with an equatorial hexagonal iridescent thin film visible using fiber optic illumination with the right angle. Other common inclusions are twinning, intersection tubes and healed fissures.

Notes about the Kenya gemstone mines pages (Edited on Oct 10, 2008)

These "Gemstone mines of Kenya" web pages presents the result of the two gemological expeditions to East Africa in Jul. and Aug. 2005 and Oct. 2007. They were build with the support of ICA (The International Colored Stone Association) and particularly of ICA ambassador to Kenya Suzie Kennedy and her husband Kennedy Khamwati for the Kenya part. Kennedy was nice enough in 2005 to take us to visit all the ruby and tsavorite mines we wanted to visit. His help, presence and permanent support was highly appreciated. In Oct 2007 we were helped in the field by ruby and tsavorite miner and ICA member Genson Micheni Musa, the owner of the Tsavolite mine near Tsavo. Micheni support was also very much appreciated.
I want here to dedicate these pages to Kennedy and Micheni as without them I would not have been able to collect and share all these notes about gem mining in Kenya.

The Jul. and Aug. 2005 expedition was a join expedition by the AIGS gemological Laboratory in Bangkok, Thailand (where I was then the Laboratory Director) and the Gubelin Gem Lab, in Lucerne Switzerland. I was then traveling with Jean Baptiste Senoble, one of my former AIGS gemology student, working as I write these words in 2008 for Nomad's Co Ltd, a Bangkok based gem dealer.

The Oct 2007 expedition was also part of a larger expedition to East Africa I lead in collaboration with gemologist Richard W. Hughes. I was then gemologist for the Gubelin Gem Lab. Two young gemologist and former AIGS students: Guillaume Soubiraa and Michael Rogers joined me in this expedition as well as One of Guillaume Soubiraa friends from Madagascar: Philippe Brunot.

The purpose of these expeditions was to visit ruby, sapphire, alexandrite, emerald, tsavorite, tanzanite and tourmaline mines in Kenya and Tanzania for gemological research purpose. Origin determination of gemstones like rubies and sapphires is an important part of the daily work at the Gubelin Gem Lab and it is important for a gemologist specialized in origin determination of gemstones to collect data directly at the source in order keep his knowledge of the world gemstone mining areas updated. As a former tour guide, turned into a gemologist, it is my pleasure to share the benefit of these expeditions with you and I hope that it will benefit to the people who welcomed and helped us in the field.

Please visit the other Kenya pages on

1 a) Kenya, a Gemstone safari: Kenya main page

1 b) Kenya, Summer 2005 expedition report.

2) On the way to Tsavo: The Simba ruby mine:

3 ) Tsavo, Mengare Swamp: The "Rockland" (former "John Saul") ruby mine.

4 ) Tsavo, Mengare swamp: The "Aqua" (former "Penny Lane") ruby mine.

5 ) Tsavo, Mengare Swamp: The "Equator" ruby mine.

6) Tsavo, Mengare Swamp: The "Hard Rock" ruby mine.

7) Spinels from Kasigau:

8) The Tsavolite Tsavorite mine:

9) The Bocrest Tsavorite mine:

10 ) The Nadan Tsavorite mine

11) The Baraka Tsavorite mine

12) The Scorpion Tsavorite mine

13) Color change garnets:

14) The Baringo ruby mine

Special thanks,
to all the Kenyan authorities we met which provided us support and help, to the miners who welcomed us at their mines, shared with us their time and their life. Your support and welcome was much appreciated!
I hope that this report will be useful to all people we met in Kenya and to all the people interested in the gem trade from the production areas in Kenya to the consuming markets and for all gem lovers around the world.

Now I would like to give a more personal thanks to the following people as without their help and support during these expeditions to Kenyia, I would not have succeded in these expeditions:

First thanks to my traveling companions which helped to finance, to organize and to make this expedition a succes:

Jean Baptiste Senoble currently working for the Nomad's company in Bangkok was my gemology student at the AIGS, in Bangkok and became then one of my regular traveling companions to gem markets and mines around Bangkok. He was my traveling assistant during the 2005 gemological expeditions to Vietnam, Sri Lanka, Madagascar, Kenya and Tanzania. We returned together in Tanzania and Madagascar in 2008. Without his help and support these expeditions would not have even been possible.
All the best to you JB!

Guillaume Soubiraa (from SMDA in Madagascar) and Mike Rogers, two former students of the AIGS in Bangkok and Philippe Brunot, one of Guillaume childhood friends from Madagascar were my travelling companions while visiting Kenyan ruby and tsavorite mining areas in October 2008. Thanks to their presence, support and presence this expedition turned to be a pleasure and a success.

All the best guys and great thanks!

These 2005 and 2007 expeditions to Kenya tsavorite and ruby mines would not have been possible without the help of local members of the Kenyan gem trade:

Suzie Kennedy is the current ICA Embassador to Kenya. With her husband Kennedy Khamwathi, they are some very active members of the Kenyan gem trade. Our 2005 and 2007 expeditions were possible thanks to their help and support.

The presence of Kennedy each day during all our 2005 expedition was very much appreciated and so useful to the succes of this expeditions.
Really thanks to both of you!

Genson Micheni Musa is a Kenyan ruby dealer which turned into a tsavorite miner in Kasigau area. His mining company "Tsavolite" is located just near the famous Tsavo National Park. Micheni was a wonderful and friendly guide during our October 2007 expedition. His knowledge of the Kenyan gem trade and of the Tsavo area was very useful to the success of our expedition.
Thanks Micheni!

Finaly I dont want to forget to thanks the Gubelin Gem Lab in Luzern, Switzerland, my fellow gemologists and colleagues working there for their support in the realization of this expedition.

Interesting Links and recommended readings about gemstones from Kenya:

"Gemstones and Jewelry in Kenya, 2005" from the Kenyan EPZA "Export Processing Zones Authority"
"The mineral industry of Kenya and Uganda, 2002" by Thomas R. Yager
"The mineral industry of Kenya, 1998" by Philip M. Mobbs
"Geology of sapphire and ruby deposits - The example of the John Saul Ruby Mine, Mangare, Kenya": The PHD thesis of Dr Cedric Simonet. A must to read work for those interesting in Kenyan ruby and sapphire deposits.
"General setting of coloured gemstone deposits in the Mozambique Belt of Kenya" and other publications about gem deposits in Kenya on Cedric Simonet's website.
"Geology and gem deposits of Kenya"
"The Kimbo ruby deposit": An excellent study of the John Saul mine by Dr Cedric Simonet, a former manager of the mine for Hard Rock Mining.
"The John Saul Ruby mine": On Swala Gem Traders website, an interesting article about the discovery of rubies in Tsavo by American geologist John Saul.
"Savanna rubies ": by Creative Gems, an interesting attempt to brand rubies from Tsavo.
"With Open arms" A Kenyan farmer found precious bounty in his barren fields. By Denis Maina Gathanju
"Kyanite mining in Kenya", Touchstone mining company
"Star sapphire from Kenya", N.R. Barot, A.Flamini, G.Graziani, E.J. Gubelin, Journal of gemmology, 1989,21,8
"A new sapphire deposit, Turkana, Kenya", T. Themelis, Gemological Digest, Vol.2,No.4,1989
"The Growth of rubies in south -east Kenya" R.M. Key and J.O. Ochieng, Journal of Gemmology,1991,22,8
"Pink sapphire from Kitui, Kenya", Dr N.R. Barot and Dr R.R. Harding, Journal of gemmology,1994,24,3
"Golden tourmaline from Kenya" Gems and Gemology, Summer1996, pp135-136
"Kenya, a mining journal supplement, 2007" by Mining Communications Ltd 2007, London
"Colour-changing chromiferous tourmalines from East Africa" Prof. Dr H. Bank, Dr U.Henn, Journal of gemmology, 1988,21,2,pp.102-103
"Chemical fingerprinting of some East African gem rubies by Laser Ablation ICPMS" A.H. Rankin, J. Greenwood, D. Hargreaves, Journal of gemmology, 2003,28,8,pp.473-482
"Geology of the Yellow mine (Taita-Taveta district, Kenya) and other yellow tourmaline deposits in East Africa" Dr.C.Simonet, Journal of gemmology, 2000,27,1,pp.11-29
"Kenyan rubies exported to Thailand", Gems and gemology, Winter 1986, p.247
"Update on ruby output in Kenya", Jewelry News Asia, No170, October 1998, p.63
"An update on the John Saul ruby mine", Gems and gemology, Winter 1999, pp.213-214
"Exotic origin of the ruby deposit of the Mangari area in SE Kenya" A.Mercier, P.Debat, J.M. Saul, Ore Geology reviews, Vol.14,1999,pp.83-104
"The Dusi (Garba Tula) sapphire deposit, central Kenya - A unique Pan African corundum-bearing monzonite" C.Simonet, J.L. Paquette, C.Pin, B. Lasnier, E. Fritsch, Journal of African Earth Sciences, Vol.38,No.4,2004,pp.401-410
"Un grenat vert: la tsavorite" S. Heppe, Revue de gemmologie AFG, No.99,Juin 1989,pp.5-7
"Tsavorite, une pierre Africaine", V.Pardieu, Revue de gemmologie AFG, No154, Decembre 2005, pp.8-11
"Les tourmalines magnesiennes d'Afrique de l'Est", C.Simonet, Revue de gemmologie AFG, Septembre 2006, pp.4-7
"Le grenat vert tsavorite: Presentation et debat", C. Bridges, Revue de gemmologie AFG No161, Septembre 2007, pp.4-7
"Saphirs et rubis, Classification des gisements de Corindon", Le Regne Mineral, No.55, Jan-Fev. 2004
"The ICA 2006 World Colored Gemstone Mining Report", InColor, Spring 2006
"Rubin, Saphir, Korund, Schon, Hartselten, kostlar", extraLapis No15, 1998

Interesting Books about Gemstones from Kenya:

"Gemstones from East Africa" by Peter C. Keller (1992)
"Ruby and Sapphire" by Richard W. Hughes (1997)


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Important Note: Vincent Pardieu is an employee of GIA (Gemological Institute of America) Laboratory Bangkok since Dec 2008. Any views expressed on this website - and in particular any views expressed by Vincent Pardieu - are the authors' opinions and do not necessarily reflect the opinions of GIA or GIA Laboratory Bangkok. GIA takes no responsibility and assumes no liability for any content on this website nor is GIA liable for any mistakes or omissions you may encounter. GIA is in particular not screening, editing or monitoring the content on this website and has no possibility to remove, screen or edit any content.