Cutting a flawed but not an impossible dream.

In the world of my dreams, the tourmaline runs large, colorful and clean.  This is certainly not the world I  live in and I am not sure that I would want to cut in it either.  I remember a documentary on diamonds and an owner of an upscale diamond cutting establishment commenting on the perfect crystals he had cut into the world’s most perfect diamonds verse the Indians putting out junk from practically industrial grade rough.  I thought then and still think that getting a decent stone out of a lower grade of rough is a lot more challenging than getting the perfect cut out of the perfect rough.

As the tourmaline market out of Africa has deteriorated and the collection grown, my need for flawed rough with something different in color , has become more intense.  I have also found that the challenge to get a decent stone out of flawed rough,  gives me more satisfaction than I would get from cutting the perfect pink over and over again.  Fortunately my principle dealer out of Africa has been caring more larger pieces of flawed rough with good color, because of the lack of top quality material.

The piece of rough I will be focusing on is posted below.  It had the properties I hope to find in lower grade rough that is suitable for my efforts.

included rough This piece of quite included rough weighed about 60 carats. I cut four acceptable gemstones from it. 2013

About 60 carat, cobbled rough from which the four ovals were cut.

1.  A good size of 20 plus carats that gives me a chance to slice, grind and orient the rough and still have a chance to get a decent sized stone.  I certainly don’t expect a good yield in weight and if I got a decent 3 carats gemstone out of the 20 carat piece that would be fine.

2,  Good color should probably be first, but somethings are so obvious to me that I focus on the more problematic of the roughs properties first.

3.  The rough or at least an area of the rough, should look glassy even though it is flawed.  This means that I want decent crystal (transparency of the tourmaline) between and or around the flaws.

4.  Major flaws that may endanger the integrity of the finished gemstone or at least make their inclusion unacceptable, should be either on the edge of the rough or glassy area or where you think you can slice the rough into usable pieces.

So now that I have this around 60 carat piece of wonderfully colored rough that had been cobble (broken to remove waste)the first step is remove surface junk that could never be incorporated into a faceted gemstone.  This should revel the internal flaw structure of the rough.  It can vary quite a bit with tourmaline, but with this rough there was a number of major flaws that required the slicing of the rough into four pieces.

Now I have really four separate pieces of rough to play with for the price of one.  Unfortunately the amount of weigh loss when I used my saw is significant and I never slice anything without looking at the options.  In this case it was a not a close call

Now I remove any parts of the four pieces of rough that  can not be used in a gemstone.  Keeping in mind that I want to orient any remaining flaws as close to perpendicular to the table as possible.  This limits the profile of the flaw when you look at the nascent gemstone face up.  I also try to remove any flashers that I see or minimize their impact threw the placement of the table.  I also tend to stay away from emerald cuts because they display flaws too well when the flaws are under the table.  I have very little regard for the position of the optical axis.  (I have never bought rough to make this effort that had closed ends.)

I have seldom run into problems with polishing tourmaline because of its flaws.  A bigger problem is how different a facet perpendicular to the principle axis (s) can be from the rest of gemstone.  This is certainly not unique to included stones, but since these four gemstones came out in completely unknown orientations (the tourmaline was not dichroic) you can be surprised when the c axis pops up.  It was not particularly a problem with these gemstone.

Included bright blue green oval This oval was one of four stones cut from one large cobbled piece of rough. It is significantly included and has only decent crystal. The non dichroic, well saturated, blue green color is a great medium tone level. It weighs 3.86 carats.

This oval weighs 3.86 carats and was cut from the rough.

Included bright blue green oval This oval was one of four gemstones cut from a large cobbled piece of rough. It is included and has only decent crystal. Still it is bright, with a medium tone level of well saturated blue green color. It weighs 2.85 carats.

This oval weighs 2.85 carats and was cut from the rough.

Included bright blue green oval This oval was one of four cut from a large cobbled piece of rough. It is included and with only decent crystal. Still it is bright and has a moderate tone, well saturated, blue green color. It weighs 3.42 carats.

This oval weighs 3.42 carats and was cut from the rough.

Included bright blue green oval This oval was one of four cut from a large cobbled piece of rough. It is included and with only decent crystal. Still it is bright with a moderate tone level, well saturated, blue green color. It weighs 3.70 carats.

This oval weighs 3.70 carats. and was cut from the rough.

Now I will leave it to you, as to whether the four posted gemstones that I cut from the rough posted above are acceptable to you.  They are all visibly included, with one having better crystal than the others, but they all share a great color with a medium tone level.  They are all fine additions to the collection, even if the less than 15 percent yield (flash, I finally got a good weight on all four and I got about a 23 percent yield, most exceptional) and the residual inclusions, make the purchase of the rough, less than an ideal commercial undertaking.

The bottom line is that they are pretty and I had to work hard to get it that way.  If I could have found a clean piece of rough with that color, it would have had to be pretty small for me to be able to afford it and it would have been a whole lot less fun to cut.  ( Still I would have gotten it if I could.)

Bruce

An addendum to this story brought to by the collection.  When you have a selection of tourmaline in many colors to compare a new adventure with, do it.  Well I knew very well, which, much more expensive stones, I was looking for and I have posted two of them below.   The first one is from Afghanistan and is included, but to a lesser degree then the four newbies.  Still the colors are very similar and the price difference significant.  The second stone is from Mozambique.  I know that only because it is cuprian.  I did not buy it as cuprian, but I discovered it with my spectrometer.  It is also included, but with better crystal than the four newbies.  Still the colors are very similar.  All the gemstones are bright, but the cuprian does not have the neon look.  A look that is expensive.

Included, but with a high grade blue green color, Afghanistan  #771 This square Barion cut is bright and flashy, but included. It has a great middle tone level, blue green color. It came out of a large lot of similarly colored tourmaline, but less included crystals. It weighs 6.68 carats. Afghanistan

This square Barion cut weighs 6.68 carats, came Afghanistan and was called sea foam by the dealer.

Included bright blue green oval cuprian. This included bright blue green oval is not dichroic. I did not buy this stone as cuprian and it does not have the neon look. Still it has a great medium tone and is flashy. It weighs 4.97 carats.

This oval weighs 4.97 carats and is cuprian and came from Mozambique.

Comments,

Bruce again.

 

 

 

About Bruce Fry

I was born in Summit, NJ in 1947 and graduated from Summit High School in 1966. I graduated from the Colorado School of Mines in 1970 and after spending another year in graduate school, I left to see the world of Brazil. After spending some more time discovering myself, I ended up working for the Commonwealth of Pennsylvania for 32 years as an Air Quality Engineer in the Department of Environmental Protection. I retired in 2007 and took up faceting gemstones again after a long hiatus that reached back to my twenties. I had started cutting cabochons when I was 13 and bought my first faceting machine when I was 15, but ran out of money and time until I retired.
My great love in gemology is tourmaline and the collection presented here represents my effort to get as much beauty and variety in the colors of tourmaline as I can. I was particularly lucky in being able to get unheated cuprian tourmaline before copper was discovered in gem grade tourmaline from Mozambique.

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