Tucson 2012

[VapidLapid]

For tourmaline with a very dark, or closed C axis, you need to minimize this axis. To do this, you use very steep angles on the C axis plane. Opposed bar cuts work very well for these stones as the ends are cut at around a 70 degree angle. If you tried to cut a traditional cushion or round from a closed axis stone, the finished stone would be just about totally closed up, and you would have a black stone. Often green tourmaline crystals have an open C axis, but not as nice a color, so the same types of cuts are used on these stones to minimize the undesirable color.

I don't have this stone any more, but I would think the C axis on this one was closed or almost closed, yet with the step end angles the effect of the closed axis is greatly reduced.

I would naturally expect that if the stone was cut on the c-axis, but what if it was cut on the a or b? Wouldn't it then at least be bright twice a day at 12 o'clock and 6 o'clock?

 

[Pandora II]

Vapid, that's exactly the type of stone I see as Imperial Garnet. They have a more glassy look, not the worn look of the malaya garnet.

Personally, I like the different "trade" names for the garnets. It's clarifies what you are talking about, and it more understood. Take the green grossular garnets, if you call one a tsavorite, people picture a darker green compared to a Mereleni Mint which would be the lighter green. Same thing to me with these Malaya garnets. I don't think its a sales pitch, but rather a means to communicate better. Bill Hanneman has a book "Naming Gem Garnets", that goes into great depth on the composition and properties of different types and mixes of garnets. In the book he identifies a Malaya as a mix of Pyrope Spessartite, or Mg1.6 Mn1.2 Fe0.16 Ca0.04 Al2(SiO4)3
I think it's easier to just call it a Malaya! He goes on to list the refractive index ranges of these various garnets along with the spectra. All becomes very complicated with a lot of overlapping characteristics.

I would agree to a certain point.

Terms like tsavorite, rhodolite, malaya/malaia, mali, anthill are useful and mean I can picture exactly what is being discussed. I know straightaway that a Mali is a grossular/andradite mix - I suppose it could just be called a Grandite Garnet though...

On the other hand terms like blueberry rhodolite, mandarin, umba etc are not my thing - just tell me that you have a bright orange spessartite please.

Bill Hanneman's book is brilliant if anyone gets a chance to read it.

ETA. IIRC, a Malaia should be a peachy pink colour with dark platelet inclusions.

 

[chrono]

I had my suspicions about the state of the market but to hear it as a fact is disheartening.

Trade name is there for a reason, to help describe the stone to the buyer, which I feel is helpful. Unfortunately, it has become overused by unscrupulous and uninformed vendors which makes the trade name useless in the end or as a means to charge more for something the stone clearly isn't. I've seen my fair share of tsavorite garnets where the stone is too light in tone to be so, too many Mandarin garnets to count and etc.

 

[mastercutgems]

I have to agree with Chrono I know it will shock many... LOL ... Just joking Ms. Chrono; I respect you more than you will ever know

I think trade names are important with especially garnet... I know there are so many blends of that family it can go on for days and especially Tanzanian material as it is a Hodge-podge or cooking pot of blends of garnets..

Now I do also agree with Gene as the names have been so abused and overused like Mandarin garnets, tangerine, etc. it makes you think you are in a grocery store instead of a gem market... Then you see the brown slide into the color with the aide of Photo-shop you will not see it until it arrives at your door... Such a shame; but that is so true with so many things in this world today; people are starving for the almighty dollar; but there are many of us that care more about being as correct as possible over the love of the buck...

We love our gemstones and try to be as accurate as possible in our descriptions..

There is another garnet that is fairly new from Tanzania and that is the Lindi garnet which I believe is a grossular rhodolite spessartite blend as well and it is a pastel pink with a tint of orange kind of like the Pad. color but there we go again with a name that has been abused...

Oh well; it is tough and I guess we all will have to deal with this the best we can; call it what the people from that country call it; and give the very best verbal description we can ... do a spectral run on it if you have the equipment and let the chips fall where they may... We can pick this apart and in the end it all depends on 3 or 4 things.... Is it natural, is it pretty, is it in our budget, and do we really like it... If it passes all those tests; well buy it and enjoy it as long as you have it...

Can you tell I am bored this morning and do not want to start cutting these things LOL

Most respectfully;

Dana

 

[Sagebrush]

Gene,

Reclaim the romance, down with ites!I The discovery of African garnets beginning in the 60s has made a hash of the traditional variety names. Heck, every time a new one is discovered, like Mali for example, it falls between existing cracks. The name Malaya like the name Mandarin has a meaning that is associated with each gem. "Mandarin" is a trade name made up by a gem dealer but is much more evocative that spessartite. Mint Merelani i another great example! Below is an image of some of the Malaya rough available at the show.

R.

 

[Barrett]

I hope one day I will get to name my own garnet...[sigh]

 

[sphenequeen]

Sphenequeen,

Dominic Mok delivered an impressive and comprehensive talk on jadeite at The Accredited Gemologists Association. He has developed a new system of evaluation which is much more useful to Western gemologists. As with all gems, the trade has done its best to make connoisseurship in jadeite difficult for professionals and nearly impossible for mere aficionados . There is very little in the literature that relates directly to quality evaluation. When I published Secrets in 2003 I did not feel qualified to write with any authority on the topic. Since then I have spent some time studying the gem and do plan a chapter on Jadeite in Secrets II which I hope to finish by 2014. One suggestion; Jade for You by John Ng. It is out of print but copies can be found on the internet.

This was followed by an equally interesting presentation by Adolph Peretti on spinel.


RWW

thank you for this! i am looking for the book as we speak...

 

[Pandora II]

There's a very nice dinky wheel thing for jade that Dominic produced to go with his system if you can get hold of one.

He did a session at Gem-A back in October and the wheels were handed out at the annual conference - very interesting.

 

[Pandora II]

Gene,

Reclaim the romance, down with ites!I The discovery of African garnets beginning in the 60s has made a hash of the traditional variety names. Heck, every time a new one is discovered, like Mali for example, it falls between existing cracks. The name Malaya like the name Mandarin has a meaning that is associated with each gem. "Mandarin" is a trade name made up by a gem dealer but is much more evocative that spessartite. Mint Merelani i another great example! Below is an image of some of the Malaya rough available at the show.

R.

For me, this is the perfect Malaya colour - although I've seen all manner of different shades described as Malaya... even bright oranges and quite deep reds.

 

[pregcurious]

Thanks, Gene, for the explanation of cutting a tourmaline to minimize the C-axis. Sometimes I see these fancy cuts and wonder "why", and now it is starting make more sense. The intersection of art and science in gemstones is really interesting.

 

[Sagebrush]

Pandora,

Mok's colorwheel is a lot of fun and it is useful to develop an intellectual, technical understanding of the basis for discriminating among colors. Trying to use it to actually grade fine jadeite is problematic similar to trying to use digital images to exhibit the subtle differences in quality that characterize extremely fine gems, media that simply lack the sensitivity to capture those characteristics.

I began working on my chapter and what I have discovered after studying jadeite for the past decade, asking questions and comparing Mok's system with Ng's and Hughes and some Chinese efforts, is that attempting to translate unfamiliar Chinese terms with their deep cultural meaning and then trying to get Westerners to understand and work with them is needlessly complex and confusing. Many of the historical terms are contradictory and redundant. Some of the translations are simply inaccurate. **edited by moderator. please stick to educational posts and do not self-promote**

RWW

 

[Pandora II]

Pandora,

Mok's colorwheel is a lot of fun and it is useful to develop an intellectual, technical understanding of the basis for discriminating among colors. Trying to use it to actually grade fine jadeite is problematic similar to trying to use digital images to exhibit the subtle differences in quality that characterize extremely fine gems, media that simply lack the sensitivity to capture those characteristics.

I began working on my chapter and what I have discovered after studying jadeite for the past decade, asking questions and comparing Mok's system with Ng's and Hughes and some Chinese efforts, is that attempting to translate unfamiliar Chinese terms with their deep cultural meaning and then trying to get Westerners to understand and work with them is needlessly complex and confusing. Many of the historical terms are contradictory and redundant. Some of the translations are simply inaccurate. **edited by moderator. please stick to educational posts and do not self-promote**

RWW

I look forward to reading the new book when it's finished!

Jadeite is one of my bete noires - I nearly cried when one turned up in the FGA Diploma practical exam... the hours I had spent with bags of the stuff and it's simulants and I still can't tell the real thing half the time let alone grade it. Then you meet a Chinese dealer who can tell at 50 paces with one eye shut.

 

[chrono]

I am looking forward to hearing more updates about jadeite as well; I hear/read so many contradictionary reports and having all sorts of myth flying around doesn't help any.

 

[Sagebrush]

Pregcurious,

Here is an image of golden yellow topaz, the bleed through effect from the C axis is quite prominent in pear shapes as it is in long oval shapes. This multi-color effect is considered a fault in gems like sapphire. Connoisseurs of sapphire prefer a consistent hue across the entire face-up mosaic of the gem, In topaz, on the other hand, this gathering of color adds measurably to the beauty of the gem.

 

[Starzin]

Thanks to Gene and Richard for this discussion of the c-axis.

Connoisseurs of sapphire prefer a consistent hue across the entire face-up mosaic of the gem, In topaz, on the other hand, this gathering of color adds measurably to the beauty of the gem.

Yet I find myself shying away from gems that have a concentration of colour in the ends - of an oval for instance - while most of the gem is basically a washed out version of itself in the middle. I guess I'm talking about typically pale stones to begin with and I can appreciate the faceter's skill in bringing even that amount of colour to a less saturated gem.

But I probably still wouldn't be attracted to that topaz... how do other PSers feel about this? Does it put you off?

 

[Pandora II]

It would entirely depend on the use.

Those topaz would make fabulous drop earrings and I think the colour concentration adds to the aesthetic effect. I'd say the same about a pendant or even possibly a brooch.

On the other hand, I wouldn't be so keen on a ring.

You also need to approach the stone in the right way. I'm a big fan of andalusite for example and expect to see certain effects and concentrations of colour that are the whole raison d'etre of the stone but would be seen as a fault in another species.

 

[Starzin]

Those topaz would make fabulous drop earrings and I think the colour concentration adds to the aesthetic effect. I'd say the same about a pendant or even possibly a brooch.

On the other hand, I wouldn't be so keen on a ring.

Ah...yes, you are quite right - I can see them making beautiful earrings too. Though would I buy them for earrings if an even coloured, but paler pair were available? Hmmm...have to interrogate myself on that. Thinking outside the box often helps.

I'm not actually thinking of naturally pleochroic gems such as the Andalusite (pic posted for easy reference - don't know if this is a good representation of it, just the first I found with the distinctive colouring, and a lovely big window - or even bi-colours such as watermelon tourmaline but something perhaps like aquamarine (?) I'll try to find a picture but really the topaz is probably as good an example as any (and I do think they are quite lovely, just not for me).

ETA: for spelling and clarity

 

[Starzin]

That picture was somewhat unfair on what can be a very chameleon-like gem. So here's a few more to make up for it.

Found this comment in a squidoo lens...

Andalusite is poised to be the next beauty queen on the gem market. This beautiful multi color gems is still surprisingly affordable. It is being called the poor man's Alexandrite because of the way it can appear to change colors depending on how it is viewed.

Mohs scale hardness .5 - 7.5 before you get carried away peeps

 

[T L]

That picture was somewhat unfair on what can be a very chameleon-like gem. So here's a few more to make up for it.

Found this comment in a squidoo lens...

Andalusite is poised to be the next beauty queen on the gem market. This beautiful multi color gems is still surprisingly affordable. It is being called the poor man's Alexandrite because of the way it can appear to change colors depending on how it is viewed.

Mohs scale hardness .5 - 7.5 before you get carried away peeps

I'm not a fan of andalusite. I've seen lots of examples, and unless all the ones I've seen are awful, then to me, it's a really ugly gem. Going from olive green to brown is not something I personally like, but if there's money to be made, someone will market it.

 

[minousbijoux]

I'm not a fan of andalusite. I've seen lots of examples, and unless all the ones I've seen are awful, then to me, it's a really ugly gem. Going from olive green to brown is not something I personally like, but if there's money to be made, someone will market it.

Couldn't agree more - doubt there's likely to be a run on andalusite, but ya never know.

 

[Starzin]

There ya go then...I for one can stop worrying about missing out on something Thanks TL and Minous!

 

[Lisa Loves Shiny]

That picture was somewhat unfair on what can be a very chameleon-like gem. So here's a few more to make up for it.

Found this comment in a squidoo lens...

Andalusite is poised to be the next beauty queen on the gem market. This beautiful multi color gems is still surprisingly affordable. It is being called the poor man's Alexandrite because of the way it can appear to change colors depending on how it is viewed.

Mohs scale hardness .5 - 7.5 before you get carried away peeps

I'm not a fan of andalusite. I've seen lots of examples, and unless all the ones I've seen are awful, then to me, it's a really ugly gem. Going from olive green to brown is not something I personally like, but if there's money to be made, someone will market it.

Some are really beautiful TL. I have one that is green with some brown, red and orange and it is very pretty. I think the beauty of them is that although they can be a darker stone they still appear very lively and colorful.I am glad you posted the Mohs hardness as mine is rarely worn and has some chips I can see with a loupe. The stone was not chipped when set.

 

[Pandora II]

I wouldn't put it in a ring, but I've seen fabulous earrings, brooches and necklaces.

It's becoming quite popular over here especially in the autumn. Set along with hessonites it can look quite spectacular. It's also very sparkly.

 

[Starzin]

Tuscon wasn't such a happy experience for someone...
http://www.jckonline.com/2012/02/09/nearly-1-million-in-gems-reported-stolen-after-tucson-gem-show

 

[T L]

That picture was somewhat unfair on what can be a very chameleon-like gem. So here's a few more to make up for it.

Found this comment in a squidoo lens...

Andalusite is poised to be the next beauty queen on the gem market. This beautiful multi color gems is still surprisingly affordable. It is being called the poor man's Alexandrite because of the way it can appear to change colors depending on how it is viewed.

Mohs scale hardness .5 - 7.5 before you get carried away peeps

I'm not a fan of andalusite. I've seen lots of examples, and unless all the ones I've seen are awful, then to me, it's a really ugly gem. Going from olive green to brown is not something I personally like, but if there's money to be made, someone will market it.

Some are really beautiful TL. I have one that is green with some brown, red and orange and it is very pretty. I think the beauty of them is that although they can be a darker stone they still appear very lively and colorful.I am glad you posted the Mohs hardness as mine is rarely worn and has some chips I can see with a loupe. The stone was not chipped when set.

Perhaps I just never saw a decent example. I also don't like brown in gemstones. I can tolerate some grey, but I cannot tolerate brown. I have a four carat one that I bought many years ago when I was first collecting. It does absolutely nothing for me, although it is step cut and very clean. I can see the appeal in Fall colored jewelry though, but I would never set one as a solitaire.