March 6, 2010

Preamble

We often use things surrounding us without much thinking of their origin, and why they are this, or that particular way.  I have always been interested in old techniques and very frequently the best way to decipher a manufacturing method is to understand the reasons behind it.  Silverware design in general and shape of drinking vessels in particular, is an area of exploration of this writing.

Introduction

To understand silverware design, we have to deal with dark pages of Human History.  This is simply unavoidable.  We all like to believe in goodness of our fellow human being, but History lessons cannot be ignored.  We need to understand the role of poisons and their effects on civilization.

Poisons in Ancient World.

Here is a link to article, which is a very good introduction to the subject

Poisons In Ancient Rome

For those who do not have time to read complete text, here is an excerpt from the article.

Poisons and poisoning are frequently mentioned in Roman literature. The question whether the murder-rate and the percentage of suicides were greater than they are today is still debatable and cannot be decided with any degree of accuracy. Scholars cannot even agree on the size of the population of Rome itself at any given period, in spite of much research and many deductions. Much less can the death-rates from unnatural causes be determined. However, the crime of poisoning seems to have been much more frequent in ancient than in modern times. Perhaps this can be attributed to the absence of gunpowder and bullets.

The word venenum is derived, according to Walde,1 from Venus and means a love potion. It has three meanings from actual usage: remedy, 2 poison, 3 and magic drug or abortive. 4 The exact meaning is frequently determined by the qualifying adjective bonum or malum. 5 Veneficium means poisoning6 and practicing sorcery, 7 while veneficus or venefica was applied to a poisoner8 or maker of drugs. 9 However, in this paper we are primarily concerned with poisoning.

The first known instance of the crime of poisoning at Rome was in 331 B.C., when a high mortality, the result, probably, of a pestilence, was attributed to poisoning. Even Livy doubted the validity of the charges, but he10 gives the whole account as found in his sources. After many leading citizens had died from the same disease, a slave-girl gave information to the curule aediles that the reason for this high mortality was the poisons prepared and administered by the Roman matrons.

On investigation they found about twenty matrons, including patrician ladies, in the act of brewing poisons, which they declared were salutary. On being forced to drink their own concoctions to prove the charges false, they perished by their own wickedness. Following this, a hundred and seventy more were found guilty of the same offense. The second case of extensive poisoning is found in 186 B.C. in connection with the licentious worship of Bacchus.  After a careful and extensive investigation of four months, carried on throughout Italy, the praetor Quintus Naevius made a grand exposé resulting in the condemnation of two thousand persons. Poisoning was one of the crimes prominently mentioned with the rest.

I want to bring your attention to the underlined sentence in bold.  Bacchus was a god of Wine and Bacchus worship was basically a drinking orgy, accompanied with, let’s use the proper term, lascivious activities.  This is one of the earliest, if not the first, documented case of mass poisoning with wine.  Since, it is unlikely that many people would be targeted for assassination in this manner, we have a documented case mass poisoning with bad wine.  This is an important point for later discussion.

Poisons in Middle Ages and Onward

Let’s start with link as recommended reading.

brief history of poisoning

This website has tremendous wealth of information on subject of poisons.  Also pay attention to the links.  A very worthwhile reading. Here is an except for time conscious readers:

In the 8th Century AD, poisoning took another step forward when an Arab chemist successfully transformed arsenic into an odourless, tasteless powder that would elude detection for at least ten centuries, thus providing the sinister world of poisoners with the convenient and deadly ‘inheritance powder’.

By the Middle Ages, poisons were common trade in apothecaries, and available to the general public. While knowledge in other fields degenerated in the West as a result of religion, knowledge of poisons continued to bloom. Many academic texts were written on the subject by monks, among them The Book of Venoms (1424) by Magister Santes de Ardoynis, which told of known poisons at the time, how they worked, and how they could be treated.

Though most of these texts were unavailable to the public, the populace had their own (dubious) knowledge of poisons as well as equally (dubious) bizarre methods of dealing with poisoning, which included drinking from vessels with alleged magical properties and using charms and religious talismans to ward off poisoning. Most of these were obtained from the Jews7.

As the Renaissance surged through Europe, so did the popularity of poison as a method of disposing of people who were in the way. You could almost say that poisoning had become fashionable — certainly it was the most convenient way of migrating into the upper circle of society. The most infamous example from this era is that of the Borgia family, who migrated from Spain to Italy around 1455 and whose name became synonymous with dinner-party executions. The most well-known member of this family was the notorious femme fatale Lucrezia Borgia8, who formed a ghastly poisoners’ triumvirate with her father Pope Alexander VI9 and brother Cesare, and whose reputation as a poisoner has achieved a sort of mythic immortality.

The study of poisons during the 14th and 15th Centuries, coupled with the experimentation by Italian alchemists to create more potent poisons from classical bases, spread from Italy to Paris, thanks to the efforts of Queen Catherine De Medici10, and paved the way for a boom in the poisoners’ industry as the poisoning epidemic (and, subsequently, paranoia, especially in the upper class) surged through Europe. By 1572, at least 30,000 self-named poisoner ’sorcerers’ were running rampant in the streets of Paris. A poisoner-assassins’ guild called the Council of Ten was established in Italy during the 16th Century by a group of alchemists, to provide ‘elimination’ services for a fee. A publication called Neopoliani Magioe Naturalis (1589) by Giovanni Battista Porta served as a textbook for poisoners, especially with regard to lacing wine with a deadly concoction called Veninum Lupinum, composed of aconite, taxus baccata, caustic lime, arsenic, bitter almonds, powdered glass and honey, and shaped into walnut-sized pills. An arsenic-infused solution called Acqua Toffana, invented by a Neapolitan woman by the name of Toffana, was marketed as a ladies’ cosmetic under the guise of a ‘miraculous substance oozing from the tomb of St Nicholas di Bari’, but was famous among widows for more sinister purposes11. By the 17th Century, schools of poisoning had been established in both Venice and Rome, and women who had been elbow-deep in poisoning schemes from the start, now took their murderous crimes to a higher level by forming secret societies in which they received not only instructions on the administration of poison, but the weapons themselves. Poisoning had transcended murder to become art.

I have underlined a portion of the text to point out that wine was a vehicle of choice to expose a target of assassination to poison.  That was done because wine could go bad on it’s own, and it was difficult to prove whether poison got into the wine intentionally, or simply was a by-product of winemaking process.

One of the interesting questions to consider is how much of fear was due to actual attempts on life, and how much was because of improperly prepared food and wine.  After all, a lot of things can go wrong in a kitchen or a wine cellar.

To my utter surprise, I discovered that a mere suggestion that wine can become contaminated as a result of wine making process, are a fighting words in some circles.

I do not want to indict their motives, but resistance to that idea are mostly from individual associated with wine industry.  I suspect that they feel that somehow it could affect their business.  I want to put their minds at rest.  I am not on a crusade to put them out of business by making people unease about drinking wine.

Let’s consider what could had gone wrong with winemaking process, to turn wine into deadly poison.

There are number of fruits and vegetable that contain cyanide compounds which can be converted to deadly form of cyanide upon ingestion.  Here is text, compliments of Canadian Food Inspection Agency

http://www.inspection.gc.ca/english/fssa/concen/specif/fruvegtoxe.shtml

nothing special about this particular text, here is another one

http://www.ch.ic.ac.uk/rzepa/mim/environmental/html/hcn_text.htm

The point been is that a winemaker, facing a bad crop but needed wine to survive, because it was the only thing that he grows, could be motivated to use other fruits for winemaking, and some of these add-ons could had contained cyanogenic compounds.

My friends from wine lobby arguing that grapes do not contain cyanide and/or cyanogenic compounds, which is true, but is that a complete truth?  Let me introduce a new actor, whose name is Snow Mold.  If you are not a gardener, you probably would not know who it is, so here is the explanation

http://www.extension.umn.edu/yardandgarden/ygbriefs/p320snowmolds.html

Once you familiarize yourself with our little friend, it is time to read following text

http://mic.sgmjournals.org/cgi/reprint/116/1/9.pdf

I know it is heavy going, but stiffen your spine and persevere.  Pay special attention to references at the end.  There are appears to be a tons of literature on the subject.  Do you think that professors of viticulture, who are so often quoted, should know about it.  Snow mold is a very common fungus.  Do my wine lobby friends really want to argue that there was no possibility of fermentation vats getting some of it.  Now fermentation is carried out in stainless steel tanks, which are disinfected before every use, but it was not the case 500 years ago.  And where do you think this practice of cleaning fermentation tanks came from?

Evolution of Silverware design to safeguard against poisoning

As a goldsmith, I am interested the most in how all that was influencing design and techniques of silverware and jewellery.  The raisons d’être of goldsmithing is to meet the demand for things, which make everyday life more fun, so it is very illuminating to examine how our brethren rose to the occasion.

Let’s take look at some examples:

The earliest drinking vessels were horns.  It was believed that horn on contact with poison would vibrate and thereby inform of the danger.  Cellar master wore pieces of horns attached to silver chain.  Before tasting wine, the horn was lowered into the liquid and observed for reaction.  Silversmiths capitalized on that belief and produced number of articles for people who could afford them.  The picture above shows an example of such vessels.  It was made by Jacob Mores, who worked in the period from 1579 to 1609.

Rock Crystal was also used as poison indicator.  It was believed that upon contact with poison, the crystal looses it’s transparency.  This is happens to be a very rare piece.  It was made by Albrecht Jamnitzer, who achieved status of the master only 5 years before his death.  Only a few pieces of his work are known.  All are dated to 1550 - 1555.

Another material used for protection, was agate.  Agate was highly prized gemstone in XVI century, mostly due to believe in it’s magical properties.  Agate would not show if poison was present in wine, agate would render poison harmless, as the legends tell us.The cup was made by master Elias Lencker, who worked in 1562 - 1591

Use of the ostrich egg shell is very interesting.  A very wide-spread superstition in Middle Ages was that any egg shell, after egg was eaten, must be broken.  If not, than a witch could make egg shell grow as large as a boat and use it to get around to do evil deeds.  Ginrich Ohmsen, who made this goblet between 1636 and 1640, solved the problem by encasing the egg shell into silver cage.  Now it was impossible for any witch to turn it into a boat, and he would not be responsible for enabling witchcraft.  The egg shell would give the same reaction to poison as mother of pearl.

One would be remiss not mentioning use of Nautilus shells.  Nautilus shell was also known as “Ship of Pearls” due to high quality mother of pearl, lining it’s inside.  One motivation for using this material, could had been to associate with legend of Cleopatra, who was drinking pearls dissolved in wine to enhance her appearance.  If poison was present, mother of pearl would loose it’s sheen and transparency.  Master unknown, dated pre 1644

This is what is known as double goblet.  A smaller goblet is used as cover as well as goblet.  What is interesting about it is that repousse was used not only as decorative technique, but also as structural.  The teardrop volumes stiffened the whole structure, and at the same time showed off superior reflective ability of silver.  It should not be overlooked that on the inside, the edges of these areas would be first to react to presence of poison, so even minute discoloration would be noticeable due to it’s shape.Unknown master, dated pre 1520.

Another interesting type of silverware are salvers.  The name itself is very revealing of the purpose.  Etymology of salver from French salve, from Spanish salva (tasting of food to detect presence of poison), from salva (save), from Latin salvare (to save). Another term for this former practice of sampling food is credence.

Let’s look at some examples

Master Hans Brabant, worked 1535 - 1569.  Mother of pearl medallions function as poison indicators.

Center composition in silver, functions as poison indicator, but it does more than that.  Composition depict the finale of legend “Apollo and Daphne” when Daphne just about to be caught, turns herself into laurel tree.  Since cherry laurel was primary source of cyanide in Middle Ages, it is possible that a warning was intended.  Master Ditrich Moye, worked 1633 - 1653.

Master Hans III Lambrecht, worked 1630 - 1683.  I have included this salver not because of some unusual technique, but because of it’s composition.  Floral elements on gilded background.  The artistic sense of the goldsmith is impeccable.  This salver could have been made yesterday.  There is absolutely nothing to pin it to a particular time period.  A truly timeless masterpiece.

Conclusion

The word poison conjures up images of evil and suffering, but as we know now, it was discovered in pursuit of love.  In search for the antidote, a lot of beautiful things were created and medical knowledge was advanced.  If not for poison, the profession of goldsmith probably would not exist.  Should we be surprised by creative force of poison in general and cyanide in particular ?

As a parting gift, I will present you with this link

http://dsc.discovery.com/news/2008/01/17/galaxy-amino-acid.html

Judge for yourself.

Leonid Surpin.

www.studioarete.com

March 1, 2010

Eternity Ring DVD is the first one in series on Advanced Jewellery Fabrication.  This is to help you to make the most of it.  If you do not know what I am talking about, follow this link for more information.

I am receiving a lot of emails with various questions about different aspects of the DVD.  To address it - here is a write up to navigate around pitfalls of the project.

First, lets define “advanced hand fabrication”.  When only hand tools and basic techniques are employed, there is always a possibility of something to go wrong and render everything a complete waste of time.  It is absolutely unacceptable, from business point of view, to invest a lot of shop time and resources and be at the mercy of a chance.  A number of approaches have been developed to manage the risk existing in a project of complexity.  The techniques, and/or sequences of techniques, structured to manage such a risk, in conjunction with the goal of obtaining high degree of refinement, are called advanced hand fabrication.

Why projects fail?

Projects have a life span, can get sick, and can die prematurely.  There are 3 basic reasons for project failure:

Flawed design

An accident

A lot of small errors accumulate and make continuation of a project an impossibility

It is only the third reason that is discussed here.

Errors can be either of technical nature ( technique was applied incorrectly ), or the timeline of a project was sequenced improperly.  Some errors are fatal, while others result in degraded appearance.

The DVD shows a path leading to successful completion of the project.  You are welcome to experiment with different sequences of steps, different stone sizes, and etc…  One can learn tremendous amount, simply by doing this project over and over again, trying out different variations.

Part One:

There are two things that can go wrong in Part One.  The finger size must be determined accurately.  The thing with eternity rings is their size cannot be changed.  So from the very beginning it is important to size it correctly.

The second is not getting the joint tight enough.  The inner ring will be subject to subsequent soldering.  If joint is not tight, it will reflow.  You should not depends on anti-flux and similar concoctions  to prevent joints from reflowing.  At best they are only minimally effective.  A tight joint is a much better insurance against reflowing.

When joint is tight, only a tiny amount of solder enters the joint.  The solder actually forms an alloy with joint material, and melting temperature of such an alloy is higher then melting temperature of solder.  If joint is somewhat loose, the solder simply fills the space.  There is nothing to stop such a joint from reflowing.

Part Two:

Here I start on cluster construction by bending strip edge-wise.  This is a counter-intuitive, and it has been suggested that piercing required shape from a sheet is easier and faster.  My answer is that such a suggestion fails to take into account theoretical required tolerance, and what can be done using hand tools alone.

Whether this project “dies” or “lives” depends on how well inner ring fits inside the cluster.  Tolerance of 0.1mm, which some say is a norm for goldsmithing, is way too loose, and 0.01mm is more realistic.  But how such a small quantity can be controlled using only hand tools and only basic techniques?  The trick is in understanding the reason for such close tolerances and using techniques where precision is natural outcome, and not the result of Herculean effort.

The reason for 0.01 tolerance is due to the all round parts have some degree of eccentricity (they are not as round as they should be ). This is absolutely unavoidable.  In special applications, where perfection is required, special techniques are employed, but jewelry mandrels are not made that way and the ring stretched on a particular mandrel will have mandrel eccentricity by default.

By bending strip edge-wise to smaller diameter and stretching it on the mandrel, the same degree of eccentricity is imprinted.  So we have two parts with matched eccentricity as a natural outcome of the technique.  All we need to do is to pay attention only to dimensional tolerances, which are challenging, but not as draconian as if compensation for eccentricity would be required.

If we decided to pierce out the shape, the required tolerance would not be achieved and that would doom soldering step to fail, and thereby the whole project.  If you still not convinced, go ahead and try it.  Experience is the best teacher.

The middle of the road strategy of piercing smaller shape and stretching it, is not much better.  I am going to leave it to you to determine the reasoning, as a home work.  If you cannot figure it out, let me know and I post an update.

Part Three:

Here we solder cluster top and cluster walls.  Very critical phase !  Take some time to study the picture of completed ring.  Pause your DVD player and study it.  Part four has a 10 seconds close up.  It was provided on purpose, so take advantage of it.

Ask your self, after all the piercing and filling, how much of the original joint remained?  Not much at all.  If there are any imperfections in soldering, they may be in areas which left, and these areas are all load bearing.  Even if such ring survives setting and polishing, which is unlikely; it is going to fall apart while worn.  Not a good way to build amenable client relationship.

To insure joint soundness all the way through out, a cleanliness is a must.  If you noticed, I pre-treat surfaces with flux.  The main reason for this is to see how clean the surface is.  If flux covers the metal evenly, without any breaks, joint is ready for soldering.  Use minimum amount of solder.  You can always add more solder, if estimated amount is not enough.

Part Four:

The main thing to watch for in part four, is not to destroy what was accomplished in part two.  The bottom of scallops are shaped and it must be done so not to enlarge inside diameter.

Also diamond seats are prepared.  How to properly space them explained on DVD.  I did get a lot of questions on drilling.  The reason I drill the way it shown, is to prevent over-heating.  The drill breaks because it looses ability to conduct away swarf.  This happens because drill over-heats and swarf instead of forming a spiral, comes off as flat band.  The band cannot travel through flute of the drill and starts folding on itself, eventually jamming the drill causing it to break.  Lubrication helps only a little.  By drilling as shown, the over-heating is controlled and problem of drill breakage becomes a non-issue.

Cluster and inner ring are assembled in part four.  A few things on achieving tight fit has been mentioned before, but some questions still remain.  As you see on DVD the parts are assembled under pressure.  The fit is so tight that fingers are not enough to squeeze them together and few taps with mallet are used.

To achieve the fit - measure outside of the inner band.  Keep in mind eccentricity.  It means that you should take several measurements in different places and average it out.  Once you got you dimensions, mark a place on your mandrel, which corresponds to outside dimensions of inner ring. Once again, mandrel must be measured at several points and results should be averaged out.   The spiral is stretched to the mark.  Watch out for spiral springing back a little.  After stretching, put it back on the mandrel and verify that it is still the right size.  Adjust as required.

Part Five:

Soldering is the main even in part five and it must be done exactly as shown.  If you used to solder using soldering pick, it is time for retraining.  Remember, one mishandled joint can ruin the whole project.  It can be done with soldering pick, or tweezers, but consider the risk.  If I misplace a paillon of solder, I simply reposition it.  If it is still not good, I can do it for as long as it takes.  If solder is introduced with the pick, no corrections are possible and you will have to live with the results.  Since so much depends on clean appearance of the joints, I see no reason to jeopardize the project.  This is classical risk management.  Remember, the goal is not to demonstrate that you can solder standing on your head and holding torch in your teeth.  The goal is to bring the project to successful completion.

Judging from my mail, azure is a complete mystery to some, so I am going to spend some time on it.  Take a look at the picture

All azure patterns starts with round openings.  Many variations are possible, but I limit myself to just these.

The upper row shows sequence of cutting azure, when movement of the blade is not obstructed.  The situation are encountered in cutting underneath pave plate, which is set independently and soldered in later.   The saw blade is inserted in the opening and one corner is shaped.  It follows with the second corner, the third, and the fourth.  The result is a square.  It should be noted that blade is held angled so the other side of the plate remains untouched.  Only one insertion of the blade per opening is required.

The second row shows sequence of cutting underside of a ring.  Here blade is obstructed by the ring itself, so only a side at a time can be addressed.  It is possible to cut the same pattern as for pave plate, but it is cumbersome.  Better results are obtained with pattern shown in the middle row.  Insert the blade from left to right.  Shape on corner.  Reinsert the blade from right to left and shape the other corner.  It forms a pattern reminiscent of a rope.

Third row shows variation of the rope.  It is almost the same amount of work, but looks more sophisticated.  It is obtained by adding 2 extra cuts per corner.  The DVD has enough footage to demonstrate actual mechanics of the technique.

Azure cutting is the greatest exercise in gaining mastery of jeweler’s saw.  This is a good place to mentioned hallmarking.  Obviously, in designs like this, traditional hallmarking is not possible.  One solution is to leave an area of the underside to be hallmarked.  Since punches cannot be used, it has to be engraved.  Also, consider leaving hallmarking out.  Clients who patronize jewelers specialized in this type of work, are sophisticated enough to understand the predicament.  Clients who put metal content above all, are simply looking for investment and not likely to pay extra for craftsmanship anyway.

Prong cutting is similar to azure cutting.  Possibilities only limited by your imagination.  Here are some patterns:

February 14, 2010

The information bellow is of experimental nature. No testing as far as safety of modification, has been done. Use you own judgement whether or not it is something you want to experiment with. The information provided “AS IS AND WITHOUT ANY WARRANTY WHATSOEVER”.

Whenever there is a discussion about torches, somehow it is always on how quickly it can melt a ton of gold, and is it hotter than the sun. For my money, I want a flame just barely hot enough to melt solder; I want my torch to be as light and as small as possible; and I want to be able to adjust flame to different operational envelopes. In short, I am missing blowpipe. But, I am not missing blowing into it. Is it possible to eat proverbial cake without ever buying one?

I have been using Little Torch for many years. It is not perfect, but it was as close to my requirements, as I could manage. Still, even adjusted to produce reducing flame, the torch is a bit harsh. I have been modifying tips trying to improve operational characteristics with some degree of success. However, the type of flame that blowpipe can produce, had remained elusive, until recently.

Why blowpipe flame is different ?

Chemists differentiate two types of flame - premixed and diffusion. Premixed type of flame is exactly what the name says - fuel an oxygen were premixed prior to burning. All torches produce premixed type of flame. An example of diffusion type is the flame resulted from burning candle. In diffusion burning, oxygen is separate from fuel prior to burning, and when burning starts, oxygen diffuses though fuel. Such flame is irregular, with different temperature zones, but from jeweler’s point of view, diffusion flame is very desirable.

Another characteristic of flame is the flow of burning gases. If we adjust oxygen just right, we could observe a highly organized blue cone, surrounded by yellow envelope, and transparent outer shell. The reason that we could observe this arrangement, is because torches designed to produce laminar flow of premixed gases. The flame produced by blowpipe is very much different. It has no obvious structure, because the flow of gases is turbulent. In real life, any flame will be a combination of both types of flow, and flames would differ only in percentages of each component.

Design

All right, that was helpful. Once I understand the nature of flame, I know how to design torch tip. What needs to be realized from the very start that it would be impossible to imitate blowpipe flame completely. But, it should be possible to reduce temperature of the flame and increase the size of reducing zone. Turbulence of the flow will also be enhanced.

To reduce temperature of the flame, some oxygen must be replaced with air, and to increase the size of reducing zone, flame diameter must be increased. My theory is that it should be possible to adjust a torch so there is only enough oxygen to combine with 80% of available propane. Remaining 20% should combine with surrounding air and burn with much cooler flame reminiscent of blowpipe. It is also possible to achieve with regular torch, but commercial tip design makes it very difficult. That makes perfect sense, because designer was striving for maximum efficiency, which is to ensure complete burning of propane with almost any knob setting. My design goal is quite different.

Implementation

I started by taking one of the tips with sapphire nozzle and cutting of sapphire end. Next step was to make copper tube out of copper sheet. Take a look at the drawing bellow.

Copper tube length - 20 mm; outside diameter - 3.5 mm inside diameter - 2.5 mm; side openings - 2 mm; the distance from the opening end to the tube end is 5 mm.

Few words about side openings. They are there to supply air to be diffused into propane/oxygen mixture. For them to function properly - inside diameter, tip diameter, distance from the end, size of openings - everything must be in particular relationship to each other.

Giving formulas to calculate these variables would be a waste of time. What is needed is a practical approach. I have chosen 2.5 millimeter inside diameter, because it is more than double of original diameter. By increasing diameter, I am increasing zone of low efficiency, which makes task of finding required knob setting easier. The distance, where side openings should be, is determined by inserting torch end and marking where the tube touches the tip. Distance from tip end to the mark is the required distance. Drill two small holes with 0.5 mm drill, insert tip inside the tube and open propane. When propane is lit, there should be some evidence of air mixed in. If propane burns like with the regular tip, the openings are too small. Increase them slightly and try again. Increase only a little at a time. If you make them too big, propane would be going out all the time. Discard the tube and start all over again.

When satisfied with propane flow, add a little of oxygen and the flame should form. This tip requires less oxygen to operate than regular tip. The flame is cooler and that is exactly what I want. After all dimensions are finalized, the tube is soldered to the tip.

Pictures bellow show torch with modified tip and how flame should look when side openings are of correct size.

Study the picture of the flame above. At the very root, we see 2 white spots. These are the streams of air from each opening forming sub-zones. These spots are transitioning into 2 turquoise-blue zones, which a bit further, unite into single orange-yellow zone. The envelope around this yellow zone is the most valuable part of the flame, because it has the softness of blowpipe. The color tells the story. Instead of turquoise blue, we have violet blue of propane/air mixture burning.

Leonid Surpin

www.studioarete.com

Preamble

This blog is to illustrate the beauty of Turquoise and repair the damage to Turquoise reputation as a gemstone.  The damage is a consequence of indiscriminate use of Turquoise as the name for anything remotely bluish.  Even if the blue color is completely absent, it still does not stop the gemological pimps to keep prostituting the name of Turquoise.  Regretfully, the science does provide the cover for such a behavior.  I can excuse geologists, but gemologists should know better.  While every gem is a mineral ( with some exceptions like coral, pearl, ,,,), only a minute fraction of one percent of minerals are gems.  This is true of Turquoise as it is true of any other gem specimens which have very many geological cousins, but very lonely in the world of gems.

Name Origin

Turquoise is french word which translates as turkish.  That tells us right away that gem became known in Western Europe via trade routes thru Turkey.  The primary source of Turquoise in the Ancient world were Egypt and Persia (Iran).  The best Turquoise came from Persia where the gem is called phyruza, meaning victorious.  This explains why Turquoise is the gem of choice to decorate handles of daggers, swords, and other edged weapons.  In Russia, gem is called biruza, which is phonetical equivalent of persian name, and we can conclude that Turquoise was exported to Russia directly from Persia.  Pliny the Elder called Turquoise kallalith, which means beautiful stone.

Turquoise Composition and Formation.

Turquoise is opaque, cryptocrystalline aggregate, but it does exist in crystal form.  Crystals are tiny.  The largest specimens rarely exceeds 3 millimetters in size, but they give us an indication of the real color of Turquoise.

As you can see, there is no green, no yellow, but pure blue of equatorial sky.  If only crystals existed in size suitable for faceting, the gem would rival in beauty to the finest of Aquamarines.  Alas, one could dream.

When Turquoise is in cryptocrystalline form, a some of the beauty is lost, but in skilled hands the results are nothing to sneeze at.  Take a look at image below:

Absolutely spectacular.  And again, I do not see any green or yellow, nor do I see any matrix.  That is exactly how it should be.  Let’s understand why.

Turquoise chemical formula is Cu Al6 [PO4]4 (OH)8 * 4H2O.  Here is another mineral Chalcosiderate, whose formula is Cu Fe6 [PO4]4 (OH)8 * 4H2O.  As you can see the only difference is that 6 atoms of Aluminum(Al) in the first formula are replace by 6 atoms of Iron(Fe) in the second.  In nature these two minerals form an isomorphic row, Turquoise and Chalcosiderate been end members.  The row is formed by substituting atoms of Aluminum with atoms of Iron in different amounts.  There are intermediate members like Rashleighite, Alumochalcosiderite, and others.

If instead of Aluminum(Al) replacement with Iron(Fe), Copper(Cu) is replaced with Zinc(Zn); another isomorphic row is formed Turquoise - Faustite, whose formula is Zn Al6 [PO4]4 (OH)8 * 4H2O.

Presence of Iron in Turquoise is manifested by Green hue, and presence of Zinc is indicated by Yellow.  Presence of Chromium and Vanadium can make Green particularly vivid, but is it a Turquoise?  May be in mineralogical terms; No if gem is defined as “mineral which is beautiful, durable, and rare”.  It is the purity of chemical formula which defines precious Turquoise.  Of course, the formula is a theoretical ideal.  In nature pure Turquoise does not exist.  There are always some admixtures present.  However, the quantity of such admixtures should be small, and their presence should not affect the color.

All right, you may say,  so as long as Turquoise chemically pure( with qualifications ) it is precious Turquoise?  Not really, chemical purity is not enough.  Let’s take a look at Turquoise formation.

Turquoise is a product of low temperature hydrothermal processes.  There are several morphological types of deposits, but only one particular type - nodular deposit, which produces precious turquoise.  Imagine super-saturated solution containing all the chemicals necessary to form turquoise molecule.
The solution is streaming through the cracks in a rock until it finds an opening.  At the opening, solution begins to cool off and chemicals begin to crystallize forming turquoise nodules.  Some of the nodules can reach 4 inches in size, or even more, but with increased size, the quality decreases.  The reason been is that in outer zones of a nodule, Turquoise is partially replaced with clay minerals.  Such Turquoise is soft and have chalky texture.  It looses color when exposed to sunlight and can be only used in jewellery if stabilized.  Nature plays a very rotten game.  After all the hurdles standing in a way of creation precious Turquoise, at the very last moment, nature pulls the rag from under us.  Only inner core of nodules contains what we are looking for, precious Turquoise.

Sometime, Nature throws us a bone, and instead of clay minerals, Turquoise is partially replaced by quarts and even opal.  Such Turquoise is hard and durable, cut en cabochon it will display translucency at the edges, and we can tell it apart from precious Turquoise by presence of white spots and light discolorations.  It is a very valuable material, makes great Turquoise beads, but it is not precious Turquoise.  However, such Turquoise sells at very high prices nevertheless.

What about spider web Turquoise, veinlets, and other varieties of intricately patterned Turquoise?
Such Turquoise is formed when super-saturated solution cannot find an opening.  It keep circulating inside the rock until temperature drops and Turquoise begin to crystallize inside the rock, filling up whatever crevices it could find.  This type of formation is more common than nodular and most of Turquoise on the market comes from such deposits.  It is called matrix turquoise and as a rule, it is not used in high-end jewellery.  However, there are always some exceptions.

Turquoise and Politics

Well, you would say.  Why then so many gemological authorities define Turquoise as gem material which can be blue, green, yellow, or any color in between?  My answer is that such question should be addressed to them.  Who can tell the reasons why people do things?  I definitely cannot, but I do have a theory.

May, 1887.  The greatest auction of all times held in the Ministry of Finance in Paris.  As the final step of disposing shackles of Monarchy, French Republic selling Crown Jewels.  Tiffany & Co is one of the most active participants in the auction.  They alone responsible for 1/3 of all the jewels purchased at this auction.  To everybody’s surprise, Tiffany did not even offered a bid on any of the pieces of Turquoise Parure of Duchess of Angouleme.  Turquoise blue was already Tiffany’s signature color, and nobody could understand such a strange behavior.  The answer to the mystery can be distilled from the fact that Kunz, who was the head of Tiffany gemological department at a time, was presiding over Tiffany delegation at the auction.  Kunz is rumored had sad that if Tiffany is to buy Turquoise, it is not going to come from Nishapur ( Iran ), but from New Mexico ( USA ).

This incident can offer an insight into thinking of gemological authorities on the subject of Turquoise.

I have been a practicing goldsmith for over 30 years, but my educational background is monumental sculpture.  How does one go from something as large as monumental sculpture to something as small as jewellery is an interesting question in itself.  The only explanation that I can give is that while the scale is different, the two disciplines are very similar and complement each other.

At present, my involvement with the industry is limited to operating my website www.studioarete.com where I practice my craft, and using Internet resources to communicate with other fellow goldsmiths.  I want to thank Hanuman for creating this venue.

In the following installments, I would like to explore the subject of goldsmithing from historical, sociological, and other perspectives.