New Mineral Named After GIA’s John Koivula
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 Post subject: Connoisseurship: Old Mine color (la vielle roche)
PostPosted: Wed Dec 07, 2005 10:07 pm 
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Recently I have been working of finding a gem for an important collection. The client was looking for a 4-6 carat emerald, top color, eye-clean, and beautifully cut with minor to no enhancement.

As part of this search or rather hunt because hunt it is, I have once again come upon the term "old mine" a term used by dealers to describe emeralds mined mostly in the sixteenth century from Muzo and El Chivor, the original Columbian emerald mines stolen from the Indians by the Conquistidors. (see Secrets Of The Gem Trade pp. 107 and Zucker, Gems & Jewels, A Connoisseurs Guide, pp. 54-55)

Tavernier (1678) uses the French la vielle roche, gem of "the old rock", at several places in his Six Voyages to describe Turquoise and other gems that come from specific mines, in this instance tourquoise from a valley near the Persian town of Mashad that produces the finest color.

I have been offered a beautiful emerald described as "old mine". My client has fallen in love with this term. Had I been as Wise as well forget it, I would have kept my mouth shut because I may be about to find myself hoisted up on my own sales pitch.

How does one define and "old mine stone". Well perhaps carbon dating might help. Its been used before to determine something of the age of emeralds found at ancientl digs. But, more problematic is defining what old mine means when used a a quality designation.

So I asked three experts really big names you would recognize and predictably got three separate somewhat contridictory responses. One expert maintains that old mine emeralds are not all Columbian. During the 1600-1700s not only Colombian but also Afghani emeralds were sold through Russia into India. As for color, one expert says its not color but crystal that defines an old mine stone. Another says that old mine emeralds are cloes to overcolor meaning tonally darker than optimum, slightly yellowish green but with a very distinct crystal and a honey like color. Another expert says that they exist in a color range from bluish to yellowish green have excellent crystal and a syrupy color, the best being the color of creme de minthe.

Now for UX4 and others who would like to comfortably categorize gems Here is a challenge. They say the human eye can destinguish a 1000 shades of green, more than any other hue and needless to say no lab in the world will call "old mine" on a certificate. Anyone have any wisdom on this?

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Last edited by Richard W. Wise on Thu Dec 08, 2005 10:52 pm, edited 1 time in total.

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PostPosted: Thu Dec 08, 2005 12:05 am 
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Richard...

...I agree with you - 100%. There is no substitute for the eyeballs, especially that of the pro who has looked and enumerable samples. That is why a system such as I envision would fail miserabley in making an expert color call. Yet, it MIGHT allow you and your colleagues to establish a range of colors to work within - ok, I am laughing at myself now, I am sure you guys can communicate sufficiently without such an aid.

...BUT, what if I had an exceptional stone in the weight range that you wanted - which I do. And, after I sent you hi-res pics, proportions and such, all that you needed was a better idea about the color and saturation before taking a look at it. If I were you, I would rather have a reference that would place me close to the actual color than all of the verbal impressions that I could give you.

...As far as lesser stones go: say, Aussie had a 4 ct that I wanted to look at. We could communicate everything well, except the color (s) that I find acceptable. We could range that out, with some confidence that I would get what I wanted with less worry that we would have to ship and return several times before nailing my color.

...As far as that sometimes irresistable urge to buy that 22 ct perfect natural Alex, VVS, Stoplight green to stoplight red, for BUY NOW $75....
Well, ok, I'll never buy from that seller! BUT, a seller that used a system, and, better yet, one required by ebay, would possibly give his customers a better idea as to color and saturation. And so on in the distant dealings that are more common every day in the trade.

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PostPosted: Thu Dec 08, 2005 1:40 am 
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One expert maintains that old mine emeralds are not all Columbian. During the 1600-1700s not only Colombian but also Afghani emeralds were sold through Russia into India.


That seems to be the case, the CNRS and IRD did an oxygen isotope ratio comparison on 9 "old Mine" emeralds which allowed them to pinpoint the origin of the stones, since this ratio is different from one mine to another. Unveiling the secret of old world emeralds.

Unfortunately, that probably just makes it more difficult to define what "old mine" actually refers to, since the visual characteristics of these stones are likely quite different from one to another.


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PostPosted: Thu Dec 08, 2005 5:40 am 
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Hi all,
No system could ever replace the final human eye inspection - however the human eye can also be tricked. As discussed before lighting enviroments change the looks of a stone greatly. A customer with anticipation of a certain quality, given the royal treatment in superb surroundings and being presented with a gemstone under the absolute best lighting conditions is encouraged to think the best. The Tiffany experience compared to a more humble setting with quality as good. Good clear definitions of a gem firstly and leaving the final visual inspection for the customer without pushing the expected result might help us all.

Richard - heard only last week that one miner has reopened a very old Emerald mine at Emmaville, Australia. I have no opinion/experience of the quality that used to come from here but just thought it may be of interest. The main emerald mine was opened in 1890 in an old tin mining area. I hope to see some of this stone soon.

Cheers Andrew

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 Post subject: Re: Connoisseurship: Old Mine color (la vielle roche)
PostPosted: Thu Dec 08, 2005 6:55 pm 
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I suppose the term is about looks, and that emeralds were not just Colombian at the time is history.

There is some quantity of emeralds in old jewelry left in the public domain (museum collections) - enough to see for yourself what was considered tops at the time. Unsurprisingly, many of the stones that made it into royal jewelry are clear and of intoxicating color. They ought to be striking without more human help than slight polishing, peeking from closed back settings.

Interestingly, the true geographic origin was definitely not a thing to brag about until a long century after the flow of Conquista emeralds. This, because the right to the mines' output was restricted so claiming that some stones come or do not come from a certain place should have had a quite different purpose than attesting quality.


My 2c...

The story about oil-like 'crystal' must be recent. I hear it from or about Colombian emerald presented by sellers' as some sort of connoisseur's talk. And there must be other such stories of esoteric 'old mine' qualities only known to one side of the deal...


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PostPosted: Thu Dec 08, 2005 7:59 pm 
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To the question of “old mine”; surely this is a question of standardisation. IMHO, to get your three experts agreeing, we need a standard, and accepted definition of what “old mine” is. Trouble is that “old mine” is a subjective term, and until we can agree the objects that make up the definition, we will never be able to make the last step.

To me, we need to separate the objects that might make up that definition into visible properties and environmental properties (for want of better descriptions), and agree what blend of these makes up “old mine”.

Suggested visible properties
Hue, tone, saturation and crystal

Suggested environmental properties
Age, location, provenance etc

This would certainly assist in forming the basis of an agreed “old mine” classification.

In my own collection, I use the term “sparkling transparent” to describe those really special stones, and I think Richard, this is equivalent to the term crystal that you use. But describing why one stone is sparkling transparent, and one is not is beyond me.

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PostPosted: Thu Dec 08, 2005 10:14 pm 
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intrigued by this topic, I also stumbled upon this peice of interesting reading...

http://www.sciam.com/article.cfm?articleID=00093B64-C93C-1C75-9B81809EC588EF21

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PostPosted: Thu Dec 08, 2005 10:51 pm 
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Martin, et al,

Spent the day looking at old mine emeralds, saw four. One seven carat, one four, one just under two carats and one just over a carat. The larger stones would sell in the range of six figures per carat.

Finally I compared an exceptionally crystalline top color Colombian newly mined with two of the larger stones and I saw it! The old mine stones had a "syrupy" sort of quality in the crystal. All these stones were exceptionally transparent but there was something different, a quality that would simply not be covered in the category of Crystal Yes there was a high degree of crystal but this honey like texture was simply a quality that, like the milky glow of a fine Kashmir sapphire, required additional description.

So the four Cs of Connoisseurship; color, cut clarity and crystal are sufficient to describe most high quality gems, they are all necessary, none alone is sufficient but there are additional qualities unique to certain gem varieties that require us to go beyond and would add additional complications to a standard quality grading system.

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PostPosted: Thu Dec 08, 2005 11:03 pm 
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Richard...

...Is ther any chance of photos of that suite of sweets? My brain is watering to see 'em.

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PostPosted: Fri Dec 09, 2005 1:57 am 
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Richard - it sounds as if you have discovered sparkling transparent, LOL. ;-)

On a serious note however, you are extremely lucky to have held these in your hands and been able to have evaluated them for yourself. Most of us need to go to museums to see extremely fine gems, and will probably never be lucky enough to see this elusive quality that exists in the stone. I wonder how we account for this magical something that exists in the relationship between you and the stones.

It made me think back to reading “Zen and the art of motorcycle maintenance”; by Robert M. Pirsig, and his enquiry into quality, and the subject / object divide. I used to advise staff who worked for me to read this book, to help them understand quality. Perhaps I may dust it off, and think of gems when I re-read it…

But I would have thought that a standard grading system would be over-engineered if it had to deal with all eventualities, and only a few people lucky enough to have seen for themselves the magic “syrup” rocks, would ever be able to give a valid grading.

Even you Richard, having seen this phenomenon once, may arguably be still underqualified to judge a stones “syrupiness”. So without enough high quality stones with plenty of “syrup” to share around, it is unlikely that on the whole we would need to accommodate them in our system of grading.

However, maybe I am coming at this from a small time collector with meagre funds, who certainly will never have a 6 figure sum to spend on anything but a house. Maybe that’s why I can’t see a need for a standard evaluation system to cover such extremes.

I think maybe this “above crystal” quality needs a name (and I am not seriously promoting “syrup”, or “sparkling transparent”). I also I feel as if another wonderful story is brewing for you next book Richard. (Which I think you should call sparkling transparent by the way. He he…)

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PostPosted: Fri Dec 09, 2005 3:00 am 
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Martin wrote:

I think maybe this “above crystal” quality needs a name (and I am not seriously promoting “syrup”, or “sparkling transparent”).



It has a name... probably miner's talk but reasonably popular. It is called 'gota de aceite' (drop of oil).


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PostPosted: Fri Dec 09, 2005 8:37 am 
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Ana,
Theres a new term. Love new terms. Where did you hear that one? Spanish or Portuguese?

Martin,
Several years in the future, I plan to revise Secrets and add a good many photographs of extraordinary gems. I doubt if technology is up to the task of showing this quality, however.

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PostPosted: Fri Dec 09, 2005 3:23 pm 
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Richard W. Wise wrote:
Ana,
Theres a new term. Love new terms. Where did you hear that one? Spanish or Portuguese?

Martin,
Several years in the future, I plan to revise Secrets and add a good many photographs of extraordinary gems. I doubt if technology is up to the task of showing this quality, however.


Hello Richard,

I wonder if this syrupy look isn't from years of oiling where the oil left residue since oiling emeralds has been done for hundereds of years. Have you known anyone clean out the old oil and residue thourghly and then reoil the stone?

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PostPosted: Fri Dec 09, 2005 4:05 pm 
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:lol: That was my first thought too...

Maybe they used SYRUP back then... :lol:


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PostPosted: Fri Dec 09, 2005 6:05 pm 
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No, unfortunately what tends to happen over time is that the oil dries and Canada Balsom, at least, hardens and due to differential thermal expansion forms a flaky fan-like residue.

No I am talking about a quality of transparency, like looking into perfectly clear Caro Syrup, a subtle effect. Of the two experts I spoke with one used the term honey the other syrup.

To answer your question, MJO, yes old stones are often cleaned and re-oiled.

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