Inspecting Gemstones

[canuckamuck]

As I apparently have plenty of relatives on the Burma side of the border. I often hear about gems and gold, sometimes they want me to look at it and I guess maybe they want me to buy some or find someone who wants to. We had one guy who brought a sample of gold ore, which I had assayed in Canada and it was a good gold sample, but I never saw the guy again, so that was the end of that story.

Anyhow, some other guy wants to show me some gems, apparently they are pink and they have the appearance of being liquid filled, whatever that means, he doesn't know what they are called in English. He has other types too. They want me to tell them if they are real and if they are valuable. I don't know gems very well, are there any experts here who can provide a tip or two. I don't intend to buy any of them, But I am interested to learn something new.

Please lets not turn this into a thread about scammers at the border. I am not buying anything, and I am not at the border.

[LennyW]

You could start here........ https://www.google.co.th/search?num=10&hl=en&site=imghp&tbm=isch&source=hp&biw=1280&bih=605&q=pink+gemstones&oq=pink+gemstones&gs_l=img.12..0j0i24l8j0i5i24.1110.6561.0.8825.14.14.0.0.0.0.166.1747.0j14.14.0...0.0...1ac.1.DWQFbsncumM

Edited September 25, 2012 by LennyW

[Tim207]

I had the same situation several years ago when I first started staying in Chantaburi. There are gemstones everywhere and I couldn't tell the difference between glass and ruby. Half the people I knew in the village had some connection to the gem industry, whether it was cutting stones or peddling gems in the weekend gem market. Eventually I thought it would be fun to learn more about them. What I learned is, for the most part, you have 0 chance of determining the value of a stone unless you make gems your life so forget any ideas about that. Determining what a stone is would be something you could learn if you put in some effort and had an interest but there is a lot to learn. If you are up to it I would start by googling these terms:

Visual Optics

Hodgkins Method

Visual Gemology

There is a technique to identify stones without equipment that costs hundreds of dollars that is referred to by these terms. I played with it a little and enjoyed the experience. With a very little practice you can learn to differentiate between ruby, spinel, pink tourmaline and garnet (the common red/pinks). Much of what I learned has been forgotten but I can still pick up a stone and tell if it is a ruby within seconds using only my naked eye.

My guess on your "liquid filled" stones is if this is someone telling you they are liquid filled, as opposed to you looking at them and you describing them appearing that way, they are probably rubies. I lost interest in playing with stones a few years ago (no idea where I would sell them and identifying them looses it's appeal after a while if there is no purpose) but at that time there were a lot of rubbies coming out of the Mong Hsu area of Burma that were heavily fractured. It was common practice to fill these fractures with liquified glass. If it is Burmese ruby, actually most ruby but particularly Burmese, you can shine an ultraviolet light on it and it will glow like hot lava.

Telling if they are real or not is more complicated because synthetic ruby will glow just like Burmese ruby. If he knows they are filled rubbies then he knows exactly what they are and maybe he expects you to know if they are valuable in the west as opposed to the price on the Burma border.

Post a pick if you want and I will give you my best guess.

[canuckamuck]

Thanks Lenny, that will be helpful once I have seen them. I am going to do internet research as well. But I started this thread because Thai Visa has a way of bringing out knowledgeable people that can really shortcut your research.

Thanks Tim, I will check it out. Sounds like you are well experienced. When i see the gems, I will post if it still seems interesting.

I won't see this guy again until some time in October.

Edited September 25, 2012 by canuckamuck

[Tywais]

Possibly referring to appearing 'liquid filled' it may be sapphire. I have a black star sapphire but see there are also pink star sapphire.

[quadrant]

if you want to find out whether the gems are real(natural), you have to bring them to a gemmological institute to have them tested, for example the asian gemmological inst. or the american gemmological inst. (they have offices in bangkok)

even an expert with gemstones can many times not tell you if the stone is naturally grown or is a manmade synthetic grown in a laboratory if he does not have the lab equipment at his disposal.

however, testing is quite expensive, i estimate that a test nowadays would cost you well over 1000 baht/piece. so the first question would be, how big are those stones and are they eyeclean? gemstones with noticeable inclusions have mostly low value and are not worth much. size would also be important.

since the stones originate from burma, which ist famous for their rubies and sapphires, the stones MIGHT be pink sapphires. could be something else too, however.

a cut sapphire of about 5mm round or 7x5 oval is approx. 1 carat (0,2g). colored gems smaller than that are usually not worth testing.

call up one of the institutes and find out how much they charge for testing and then select the biggest and cleanest to test if you think it might be worthwile. if the result is favourable, you might consider testing more.

hope that helps some.

cheers

[oldsailor35]

Thanks Lenny, that will be helpful once I have seen them. I am going to do internet research as well. But I started this thread because Thai Visa has a way of bringing out knowledgeable people that can really shortcut your research.

Thanks Tim, I will check it out. Sounds like you are well experienced. When i see the gems, I will post if it still seems interesting.

I won't see this guy again until some time in October.

If you are in Bangkok, then the place to go is Gem merchants/Cutters on Sukumvit by the name of LAMBERT Industries. They are very reputable doing a lot of business in Australia. If you have gem stones, they will acess and value for you, if they are rough, they will do the cutting at very reasonable prices. I have had them facet both Garnets and Sapphires for me and am very satisfied.

[rak sa_ngop]

Possibly referring to appearing 'liquid filled' it may be sapphire. I have a black star sapphire but see there are also pink star sapphire.

I think the use of the exp<b></b>ression 'liquid filling' may be referring the the heat treatment process of glass filling fissures. This is a common heat process to enhance colour and clarity of rubies and many other gem stones. I believe that Thailand is the world hub of heat treatment!

Edited September 25, 2012 by rak sa_ngop

[breadbin]

I think there are courses in BKK where you can learn how to tell fakes from genuine. I think buying good stones from bad will need experience and a simple course wont give you that. Interesting though, wouldn't mind knowing myself.

[Chittychangchang]

The majority of gemstone experts i've met here seem to freelance as tuk tuk drivers ;-)

[llso]

As some of you may know I am a Geologist. When I lived in Thailand I used to do visa runs to Victoria Point, and with a friend would go up the mountain and buy gems. I would also travel to Muang Kan (Kancanaburi) and buy gems from an old lady at the market there. She would have the real gems under the counter , and sell the less valuable fakes to the Tourist. Strangely enough I was refered to her by an older thai Policeman (my Thai Language was pretty good) who had an interesting ring. I got into a conversaaion with him and he brought me to see the old lady. UNfortunately at the time I didn't have enough disposable income to purchase too many gems. However; my friend who was a retired USAF Colonel could afford to splurge. In Burma we bought a lot of really high quality Blue Star Sapphires . I was always very sceptical of Ruby's as it almost impossible to tell from an exceptional Spinel without doing Laboratory test, as some other posters have mentioned. In fact one of the crown Jewels of Europe that was supposed to be a Ruby was later proven to be a Spinel. In my times in ASia including trips to Sri Lanka, Number 1 Gem spot in the world. I was able to buy quite a few gems . Especially some really big High quality Blue Moonstones. One of which my wife wears till this day in a 15 Karat Stone, in a Thai Gold Encased Pendant and 1 Baht Chain.

After all of my years of being only involvedonly a little bit in the Gem Trade. The most important thing is to deal with only reputable dealers. You cannot judge the mineralogy or value of any Gemstone by sight alone. Never pay too much> Buyer Beware!

LL

Edited September 25, 2012 by llso

[Tim207]

I was always very sceptical of Ruby's as it almost impossible to tell from an exceptional Spinel without doing Laboratory test, as some other posters have mentioned. In fact one of the crown Jewels of Europe that was supposed to be a Ruby was later proven to be a Spinel.

I am very surprised that a geologist couldn't tell a spinel from a ruby without a lab testing it. The traditional way to tell a spinel from a ruby is as simple as using a $10 polariscope and a 10x lupe. Spinel is singly refractive and ruby is doubly refractive. With this method you also need to be able to spot anamolous double refraction that is common in synthetic spinel but a lab is definitly not needed. Of course you could also go the more complicated route and use a refractometer to get the refractive index which will give you a pretty good idea of exactly what type of stone you have rather than just narrowing the possibilities down but those are a couple hundred dollars, require some training and is over kill for simply identifying ruby.

I think you would find the non-traditional method that I mentioned in my earlier post even more helpful than a polariscope. With no instruments of any kind it is simple to tell a faceted ruby from any other gem in seconds with just a few minutes of training. I may not be a geologist but I do know a bit about gemology.There are some reasons you would need to send a stone to a lab but differentiating between ruby and spinel is not one of them, regardless of the quality of the spinel. They may be the same color but the optical properties are very different. The Chantaburi gem market is full of gem dealers on the weekends and they certainly are not sending every stone they buy to a lab.

You are correct that many crown jewels of Europe thought to be ruby were in fact later found to be other gems, but seeing as those gems were acquired long ago before modern methods and understanding of crystal structures it isn't surprising that hundreds of years ago people couldn't tell the difference and were later found to be in error.

[DLock]

I have no doubt that a little education will help you identify the gemstones, which could easily be corundum (sapphire or ruby), spinel....or glass.

But discerning the value from a $5 stone to a $500 stone is something best left to the experts.

If you are not experienced in the gem world, I recommend you buy cut gems that you can have valued and tested for treatments, rather that rough that really needs an expert eye to see into the gem to determine what it will cut and hence, what it's worth.

Having said that, if the rough is cheap enough and you believe it to be real, sometimes it's worth a punt.

[rak sa_ngop]

Another easy way of narrowing down the identification of ruby and spinel is by UV light flourescence. You can buy a UV torch on the street for 100 baht. Ruby flouresces but generally red spinel does not. But I am told that some chromium rich spinel does flouresce.

[Tim207]

I found a link to illustrate how visual gemology works.

Take a look at this page. http://www.gemstoneartist.com/GemID.asp It shows ruby as opposed to garnet not spinel, but nothing looks like a ruby. Once you understand how to see the spectrum, spotting ruby is simple.

[canuckamuck]

Fascinating and useful posts, keep them coming.

[rak sa_ngop]

I found a link to illustrate how visual gemology works.

Take a look at this page. http://www.gemstonea...t.com/GemID.asp It shows ruby as opposed to garnet not spinel, but nothing looks like a ruby. Once you understand how to see the spectrum, spotting ruby is simple.

Really useful link. Wish I had seen it before.

Couple of points for those who want to follow the steps

Use a incandescent i.e filament light source to get a white light spectrum. Modern lightsaving lightbulbs are not 'white'. Saying that an led light bulb looks pretty white to me when looking through a spectroscope so should give the dispersive prismatic effect.

The zircon stone he is talking about is not the same as cubic zirconia (or incorrectly cubic zirconium. CZ is highly dispersive but not doubly refractive). I am off to buy a larger zircon from the Jewellry Trade Centre Silom road. The one I already have cost 100 baht but is too small to hold easily up to the eye.

Synthetic stones are available around the JTC Silom, but the centre of the synthetic trade seems to be close to Wat Ko in Chinatown - Soi Wanit. You can get a large synthetic (not glass or CZ) cut ruby for not much more than 100 baht.

Hope I get to grips with the Hodgkinson before I go blind!

[Tim207]

I found a link to illustrate how visual gemology works.

Take a look at this page. http://www.gemstonea...t.com/GemID.asp It shows ruby as opposed to garnet not spinel, but nothing looks like a ruby. Once you understand how to see the spectrum, spotting ruby is simple.

Really useful link. Wish I had seen it before.

Couple of points for those who want to follow the steps

Use a incandescent i.e filament light source to get a white light spectrum. Modern lightsaving lightbulbs are not 'white'. Saying that an led light bulb looks pretty white to me when looking through a spectroscope so should give the dispersive prismatic effect.

The zircon stone he is talking about is not the same as cubic zirconia (or incorrectly cubic zirconium. CZ is highly dispersive but not doubly refractive). I am off to buy a larger zircon from the Jewellry Trade Centre Silom road. The one I already have cost 100 baht but is too small to hold easily up to the eye.

Synthetic stones are available around the JTC Silom, but the centre of the synthetic trade seems to be close to Wat Ko in Chinatown - Soi Wanit. You can get a large synthetic (not glass or CZ) cut ruby for not much more than 100 baht.

Hope I get to grips with the Hodgkinson before I go blind!

If you are having trouble seeing the spectrum you need to vary the angle of the light. Start by looking directly at the light through the table of the stone. When you can see the light source reflecting off of all the facets, slowly rotate your upper body away from the light source and the reflections of the light inside the stone will stretch into light spectrums. The angle to the light is dependent on the refractive index of the type of stone you are looking at.

BTW, unless things have changed in the last few years, many gemologists consider this stuff voodoo. After years of training and lots of money for expensive equipment, some people have a hard time accepting that there is a cheaper and easier way. Not to say this supplants gemology training or the need for gemology tools, it is however incredibly useful.

[llso]

I was always very sceptical of Ruby's as it almost impossible to tell from an exceptional Spinel without doing Laboratory test, as some other posters have mentioned. In fact one of the crown Jewels of Europe that was supposed to be a Ruby was later proven to be a Spinel.

I am very surprised that a geologist couldn't tell a spinel from a ruby without a lab testing it. The traditional way to tell a spinel from a ruby is as simple as using a $10 polariscope and a 10x lupe. Spinel is singly refractive and ruby is doubly refractive. With this method you also need to be able to spot anamolous double refraction that is common in synthetic spinel but a lab is definitly not needed. Of course you could also go the more complicated route and use a refractometer to get the refractive index which will give you a pretty good idea of exactly what type of stone you have rather than just narrowing the possibilities down but those are a couple hundred dollars, require some training and is over kill for simply identifying ruby.

I think you would find the non-traditional method that I mentioned in my earlier post even more helpful than a polariscope. With no instruments of any kind it is simple to tell a faceted ruby from any other gem in seconds with just a few minutes of training. I may not be a geologist but I do know a bit about gemology.There are some reasons you would need to send a stone to a lab but differentiating between ruby and spinel is not one of them, regardless of the quality of the spinel. They may be the same color but the optical properties are very different. The Chantaburi gem market is full of gem dealers on the weekends and they certainly are not sending every stone they buy to a lab.

You are correct that many crown jewels of Europe thought to be ruby were in fact later found to be other gems, but seeing as those gems were acquired long ago before modern methods and understanding of crystal structures it isn't surprising that hundreds of years ago people couldn't tell the difference and were later found to be in error.

Hi Tim,

You are certainly very knowledgable about Gemology, Thanks for the info. I once bought a stone in India that was supposed to be a piece of Smoky Quartz. It had a a Rhombic cleavage so I was Skeptical. I flipped it around under a flashlight and found the correct plane and it glowed a beautiful Violet color. It turned out to be Iolite (Water Sapphire)

The point that I was trying to make is that for someone who is not very knowledgable and without any basic equipment that you mentioned it would be difficult to distinquish certain Spinels from a true Ruby. My speciality is actually not Mineralogy, but Coastal and Marine. This is what brought me to Thailand to oversee Aquaculture,and set up a Seafood processing facility years ago.

LL

[Tim207]

Hi Tim,

You are certainly very knowledgable about Gemology, Thanks for the info. I once bought a stone in India that was supposed to be a piece of Smoky Quartz. It had a a Rhombic cleavage so I was Skeptical. I flipped it around under a flashlight and found the correct plane and it glowed a beautiful Violet color. It turned out to be Iolite (Water Sapphire)

The point that I was trying to make is that for someone who is not very knowledgable and without any basic equipment that you mentioned it would be difficult to distinquish certain Spinels from a true Ruby. My speciality is actually not Mineralogy, but Coastal and Marine. This is what brought me to Thailand to oversee Aquaculture,and set up a Seafood processing facility years ago.

LL

I have no doubt you know a lot more about rocks and minerals than I do. I have no formal training. However I do know some information specific to gems and quite a bit specific to ruby. The OP was asking for information specific to red Burmese gems. With the proper knowledge these can be readily identified without resorting to complicated expensive equipment. If you are open to a new way of looking at gems I think that you would find the Hodgkinson method very interesting and helpful in your gemstone quests. Come over to the dark side, learn a little voodoo.

[rak sa_ngop]

Hi Tim 207

While we are on the subject of spinel, I have been looking to buy some black spinel gems as an alternative to black onyx.

I bought several cut Burmese? stones in Mae Sai which are black to look at but translucent one is blue one is red (200 baht a carat).

I have also bought some Thai black spinel from Bo Ploy, Kanchantaburi which is black opaque. (30 baht a carat)

Are these the same 'spinel'? The lady in the shop mentioned a hardness of 7.1 which seems a bit low for spinel.

This is complicated by the Thai use of the word Nin, which I believe is the Thai name for black spinel, but seems to be applied to black onyx as well.

Any ideas on what is real Thai black spinel?

Edited September 27, 2012 by rak sa_ngop

[bonobo]

I once saw a show on Discovery about fake gems, and people were baking less-valuable gems in a small, extremely hot oven along with various compounds, which would color the gems into higher-valued ones. The expert they interviewed said that it was virtually impossible to ascertain if the gem was fake or genuine by examining it. He said the only way to know for sure would be to cut the gem, which, of course, would lower the value of the end product.

[Tim207]

Hi Tim 207

While we are on the subject of spinel, I have been looking to buy some black spinel gems as an alternative to black onyx.

I bought several cut Burmese? stones in Mae Sai which are black to look at but translucent one is blue one is red (200 baht a carat).

I have also bought some Thai black spinel from Bo Ploy, Kanchantaburi which is black opaque. (30 baht a carat)

Are these the same 'spinel'? The lady in the shop mentioned a hardness of 7.1 which seems a bit low for spinel.

This is complicated by the Thai use of the word Nin, which I believe is the Thai name for black spinel, but seems to be applied to black onyx as well.

Any ideas on what is real Thai black spinel?

I don't know much about black spinel but I do know there are not a lot of sources. One is kanchanaburi and I don't believe any comes from Burma but I could be wrong on that. If I understand you, you seem to have purchased some very dark red and blue spinel from Burma. Those would be the same stone as the black just different colors.

I have found that many/most small Thai dealers tend to call many different stones of the same color by the same name so your problem with nin is that the dealer may not know the difference between onyx and black spinel or even care that there is a difference.

There is a short discussion here http://gemologyonline.com/Forum/phpBB2/viewtopic.php?f=37&t=4343 about differentiating onyx from spinel. As I am not very familiar with either you can check that out but in essence they say there is a slightly different luster. Onyx has a hardness of about 7 which seems to match up with what you were told. Specific gravity is very different if you have the means to check that.

Opaque stones are difficult to check without instruments. Sorry I don't have a trick for you to try.

This thread has got me interested in this again. I am curious how your experiment with viewing the spectral signatures went.

[Tim207]

I once saw a show on Discovery about fake gems, and people were baking less-valuable gems in a small, extremely hot oven along with various compounds, which would color the gems into higher-valued ones. The expert they interviewed said that it was virtually impossible to ascertain if the gem was fake or genuine by examining it. He said the only way to know for sure would be to cut the gem, which, of course, would lower the value of the end product.

Heat treatment has been done for a long time and new tricks are continually being discovered. The different ways to enhance stones and detect those enhancements is a very interesting subject in itself. That is one of the reasons it is very difficult to value stones if you don't constantly keep up with the changes.

Richard Hughes has some great articles that some might find interesting

http://www.ruby-sapphire.com/brief-history-heat.htm

http://www.ruby-sapphire.com/flux_healing_mong_hsu_ruby.htm

http://www.ruby-sapphire.com/treated_orange_sapphire.htm

http://www.ruby-sapphire.com/blue_surface_diffusion.htm

Anybody interested in gems should take a look at http://www.ruby-sapphire.com there are a lot of interesting articles that are well written and a fun read. Not just technical but also about the hunt for stones.

[Tywais]

Heat treatment has been done for a long time and new tricks are continually being discovered. The different ways to enhance stones and detect those enhancements is a very interesting subject in itself.

Another method has been to put the stones in a nuclear reactor. Working at a university nuclear research facility, we have been doing quite a bit of gem stone modification by bombarding them with ION beams from a particle accelerator. Nitrogen, Argon and Helium ions specifically. The results have proven very impressive.

We have our own lapidary lab now and the same system that implants IONs in them is used for spectroscopy of the stones. Of course both those techniques are not exactly cheap but if done in volume perhaps cost effective.

I'll try and find a photo from one of our publications showing the results.

[rak sa_ngop]

Hi Tim 207

While we are on the subject of spinel, I have been looking to buy some black spinel gems as an alternative to black onyx.

I bought several cut Burmese? stones in Mae Sai which are black to look at but translucent one is blue one is red (200 baht a carat).

I have also bought some Thai black spinel from Bo Ploy, Kanchantaburi which is black opaque. (30 baht a carat)

Are these the same 'spinel'? The lady in the shop mentioned a hardness of 7.1 which seems a bit low for spinel.

This is complicated by the Thai use of the word Nin, which I believe is the Thai name for black spinel, but seems to be applied to black onyx as well.

Any ideas on what is real Thai black spinel?

I don't know much about black spinel but I do know there are not a lot of sources. One is kanchanaburi and I don't believe any comes from Burma but I could be wrong on that. If I understand you, you seem to have purchased some very dark red and blue spinel from Burma. Those would be the same stone as the black just different colors.

I have found that many/most small Thai dealers tend to call many different stones of the same color by the same name so your problem with nin is that the dealer may not know the difference between onyx and black spinel or even care that there is a difference.

There is a short discussion here http://gemologyonlin...php?f=37&t=4343 about differentiating onyx from spinel. As I am not very familiar with either you can check that out but in essence they say there is a slightly different luster. Onyx has a hardness of about 7 which seems to match up with what you were told. Specific gravity is very different if you have the means to check that.

Opaque stones are difficult to check without instruments. Sorry I don't have a trick for you to try.

This thread has got me interested in this again. I am curious how your experiment with viewing the spectral signatures went.

Just to confirm that your spelling of kanchanaburi is correct. I tend to find it dificult to speak out Kanchanaburi and Chantaburi in the same sentence witout getting them mixed up. Chantaburi is of course a major gem trading town south of Chonburi (Pattaya).

Regarding the Hodgkinson method, I have tried it on Ruby and Spinel and there is a huge difference in spectra to be seen. I couldn't find a cheap zircon gemstone yesterday as I would really like to 'calibrate' my eye as described. Seems I wasted spending 6000 baht on a spectroscope after all ( but I can check to see if my light sources are 'white" though).

The black opaque spinel I bought in Bangkok is from a shop solely selling gems and jewellrey from Bo Ploy - Kanchanburi so I think it is not black onyx. I will have to buy some black onyx now and do some comparisons.

[quadrant]

Hi Tim 207

While we are on the subject of spinel, I have been looking to buy some black spinel gems as an alternative to black onyx.

I bought several cut Burmese? stones in Mae Sai which are black to look at but translucent one is blue one is red (200 baht a carat).

I have also bought some Thai black spinel from Bo Ploy, Kanchantaburi which is black opaque. (30 baht a carat)

Are these the same 'spinel'? The lady in the shop mentioned a hardness of 7.1 which seems a bit low for spinel.

This is complicated by the Thai use of the word Nin, which I believe is the Thai name for black spinel, but seems to be applied to black onyx as well.

Any ideas on what is real Thai black spinel?

I don't know much about black spinel but I do know there are not a lot of sources. One is kanchanaburi and I don't believe any comes from Burma but I could be wrong on that. If I understand you, you seem to have purchased some very dark red and blue spinel from Burma. Those would be the same stone as the black just different colors.

I have found that many/most small Thai dealers tend to call many different stones of the same color by the same name so your problem with nin is that the dealer may not know the difference between onyx and black spinel or even care that there is a difference.

There is a short discussion here http://gemologyonlin...php?f=37&t=4343 about differentiating onyx from spinel. As I am not very familiar with either you can check that out but in essence they say there is a slightly different luster. Onyx has a hardness of about 7 which seems to match up with what you were told. Specific gravity is very different if you have the means to check that.

Opaque stones are difficult to check without instruments. Sorry I don't have a trick for you to try.

This thread has got me interested in this again. I am curious how your experiment with viewing the spectral signatures went.

Just to confirm that your spelling of kanchanaburi is correct. I tend to find it dificult to speak out Kanchanaburi and Chantaburi in the same sentence witout getting them mixed up. Chantaburi is of course a major gem trading town south of Chonburi (Pattaya).

Regarding the Hodgkinson method, I have tried it on Ruby and Spinel and there is a huge difference in spectra to be seen. I couldn't find a cheap zircon gemstone yesterday as I would really like to 'calibrate' my eye as described. Seems I wasted spending 6000 baht on a spectroscope after all ( but I can check to see if my light sources are 'white" though).

The black opaque spinel I bought in Bangkok is from a shop solely selling gems and jewellrey from Bo Ploy - Kanchanburi so I think it is not black onyx. I will have to buy some black onyx now and do some comparisons.

since spinel is harder than onyx, you might get a hint on what you are looking at, at observing the sharpness of the facets (i assume they are already cut). if they are sharp it would suggest spinel. if the corners are rather roundish it is possibly onyx.

cheers

[Tim207]

Just to confirm that your spelling of kanchanaburi is correct. I tend to find it dificult to speak out Kanchanaburi and Chantaburi in the same sentence witout getting them mixed up. Chantaburi is of course a major gem trading town south of Chonburi (Pattaya).

Regarding the Hodgkinson method, I have tried it on Ruby and Spinel and there is a huge difference in spectra to be seen. I couldn't find a cheap zircon gemstone yesterday as I would really like to 'calibrate' my eye as described. Seems I wasted spending 6000 baht on a spectroscope after all ( but I can check to see if my light sources are 'white" though).

The black opaque spinel I bought in Bangkok is from a shop solely selling gems and jewellrey from Bo Ploy - Kanchanburi so I think it is not black onyx. I will have to buy some black onyx now and do some comparisons.

When I write Kanchanaburi I definitly mean Kanchanaburi. The name kind of twists my toungue and feels unnatural leaving the t out of the middle. I have been spending my winters in ChanTaburi for over a decade so the names are not similar to me at all, although before I had been to either I would confuse the two.

Glad to see you found the Hodgkinson method useful. I have a few tools that don't see much use anymore also. It was fun learning to use them but when someone wants me to look at a stone I rarely have any equipment with me. Ruby being so distinctive, it is easily determined if a stone is or is not ruby with a quick look. Lots of fun.

[rak sa_ngop]

I managed to pick up a 3 ct blue zircon, unheated from Ratanakiri, Cambodia for 1600 baht. Nice oval eye-clean (to my eyes) stone. Should make a nice ring when mounted.

The seperation of spectra using the H method is quite fantastic. Definitely worthwhile starting out with a highly dispersive double refracting stone like zircon because it can be a bit confusing seeing overlapping images. Sometimes overlapping images arise from different reflection/refraction paths within the stone so zircon helps to get ones eye in.

Onwards and upwards!

[pigeonjake]

hi to all you experts, great reading,, thank you,

ive been working in scotland, still am, and ive bought my wife a beautiful tanzanite ring to bring home with me,

they say its rarer then diamonds is there any truth in this? dosnt matter as it is very beautiful

thank you jake