The Quarterly Newsletter of the Canadian Institute of Gemmology (C.I.G.)
Here a brief summary of my itinerary: Hanoi - (Hue - Hoi Anh - Nha Trang) - Saigon - Siem Riep (Angkor Wat) - Pailin - Chanthaburi - Bangkok
Vietnam, the latest Asian dragon to awake from its slumber. I highly recommend this beautiful country as a travel destination: along its 3,500 km long coastline you will find some of the country's oldest towns and many beach resorts. The food is excellent, the people are friendly and prices are very affordable.
After reading an article about Gemstones in Vietnam and personal recommendations I decided first to go on a 3-day Halong Bay excursion which included a visit to a small pearl farm.
These are usually run by families but the output is rather limited.
Here a brief report about Vietnamese Akoyas.
From Hanoi one can also travel to the ruby and spinel mines in Luc Yen and Yen Bai. But it is still a time consuming trip (others have done it); there are also restrictions for selling gems to foreigners.
Looking around in jewellery stores in Hanoi and other cities I saw very little of good quality rubies and spinels; only crystals in their host-rock were offered to tourists. During GIT 2008 we heard about Sapphires and Zircons in South-Central Vietnam and Aquamarines from Thanh Hoa.
Due to lack of time I took the plane and made several stop-overs along the coast and ended up in the slightly chaotic Ho Chi Minh City (Saigon). From there I continued to Siem Reap (Cambodia) for the obligatory visit of the Angkor Wat temples.
I found one full day sufficient for visiting several sites and started the arduous and hot journey towards Pailin. The road to Battampang is still under construction and mostly paved but further on little has changed since I was in the area some 10 years ago. The town of Pailin is now a "dusty hole" and the famous sapphire mines have been totally bulldozed and worked out. However, there a new mines in the hills operated by families searching for treasures.
I was glad when I arrived at the Thai border and Chanthaburi was only an hour away.
I spent a whole Saturday with Dave Fortier, G.G. and Mr.Rho who has lived in Chanthaburi for over 25 years and has his own booth equipped with basic gem testing instruments. Sitting there and looking at hundreds and hundreds of stones passed on by dozens and dozens of gem dealers coming and going was one of the best free gemmology lessons I had quite awhile.
At times I was overwhelmed and I can see how an unexperienced buyer can easily get carried away. Everyone knows that the Thai dealers are one of the toughest and I learnt my lesson when I wanted this 5.22 ct glass filled ruby (see below) desperately. They must have sent the message around because dealer after dealer wanted the same inflated price. I won't disclose the price I finally paid; I am sure it was too much.
On the left several brilliant green sphene, two garnets; flawless bi-colour tourmaline and inexpensive tourmalines ($ 10 - 30/ct) in sizes from 1 - 3 ct.
I highly recommend a visit to Chanthaburi; where else in Thailand do you get a room in the best hotel in town for under $ 20 including breakfast buffet. Contact Dave through his blog The Gem Vault; he will gladly assist you.
The following material was offered as treated ruby from Mozambique. I am a bit sceptical because most of the glass-filled material originally came from Madagascar. However, I made some interesting observations: the treated rough had some black markings for which I do not have an explanation; they must be caused by the treatment process. I also put the polished ruby on my LED light to see the typical inclusions of the filler. Mr. Rho showed me some material under the microscope which was untreated and costs 10 times as much; one could see the difference but not when looked at the gem without magnification.
In the GLR&T lab I put the 5.22 ct "ruby" on the refractometer and it gave a reading of RI 1.762 and 1.1770 for corundum.
However, on the polariscope under crossed polarizers and while rotating the stone it remained "bright" indicating an aggregate.
This "gem material" is selling for around $ 10/ct and should properly be called "composite ruby". See AGL Disclosure Policy.
While at the Chanthaburi markets I saw a huge amount of tourmalines at rock bottom prices. I purchased five with total weight 11.68ct for $ 65; they were sold as Mozambique tourmalines but I am not convinced. When asked about the origin of other gems the dealers often answered "Mozambique"; they simply do not know.
Back in the lab I tested the stones using basic gemmological instruments and an immersion cell. They all tested tourmaline: four of them had the c-axis perpendicular to the table which is a bit unusual; the pink stone shown here under immersion did not. The interesting inclusion is a fissure (reaching the surface) filled with a substance I cannot identify due to lack of instrumentation; but it appears to be of natural origin.
Gemmologists should always remain alert and share their observations with fellow gemmologists. Often the cutters know first hand as it was the case with the unfortunate andesine/labradorite fiasco back in May 2008.
I tested 3 laser pointers (from left to right): a 405 nm blue-violet, a 532 nm green and 650 nm red 5 mW output laser.The red and green laser pointers cost around $ 10 (on e-Bay); the blue-violet laser around $ 100 but prices are falling.
As one can see (left image, using Ocean Optics USB2000+ spectrometer)) the green laser has two emission peaks (at 532 nm and 800 nm) and is therefore of little use for fluorescence studies; however, it is a powerful laser pointer with a distance of up to 1.5 km.and will replace the red laser pointer used in lecture halls.
ALWAYS USE PROTECTION WHEN EXPERIMENTING WITH LASER POINTERS
I repeated the fluorescence studies I conducted earlier with the 395 UV LED (see CIGem NewsJanuary/February 2009) using two yellow synthetic diamonds (in chart pink and yellow) and a blue table cyclotroned natural diamond (in chart blue). The results were very similar with the exception of one of the yellow and the blue diamond passing the 405 nm line to the spectrometer; the output of a laser is much more powerful than that of a LED light source.
Personally I do not find any advantage of using the blue-violet 405 nm laser for gemological studies. One MUST wear protective gear; some people may not see the blue-violet laser emission and can damage the eye if the laser is inadvertently left switched on. At the moment they are still expensive compared to UV LEDs.
I also investigated another potential of laser pointers in laser tomography using a gemmological microscope and the immersion cell. We have camera equipment to see both in the UV and IR range. However, the output of 5 mW is not sufficient to penetrate the stone enough. This type of experimentation has to be left to university labs where more powerful lasers are available.
An interesting website about laser pointers and their use is found here.
Next Vancouver week-end seminar
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