Hunkers in the Hole, Adventure in Cutting Big Semi-Facet Rough.

In the effort to produce a top quality (AAA) piece of tourmaline rough a whole lot of cobbling, clipping and grinding goes on.  Now everyone loves the perfect piece of rough that can produce the perfect gemstone with a great retention of weigh, but in my quest for color, the exclusive cutting of this type of rough is just not reasonable or affordable.

Lately I have been even more focused on large (on the order of 100 carat) pieces of semi-facet tourmaline rough.  Now this type of rough is not extensively worked with by the dealer/preparer of the rough.  There is not enough promise to put the work in and there might be surprises that would render the rough only suitable for beads/cabs etc.  And there is always the chance that some cutter likes the color or is just a gambler at heart and will buy gems truly in the rough.

Well I like the challenge of getting the best out of tourmaline rough.  I never expect flawless gemstone from semi-facet rough even when I accept extremely low yields and smaller stones.  Still I can get some great colors and acceptable gemstones for the collection, that  broadens in color as I make progress in my quest for more and more color in tourmaline.

So in support of my addiction to tourmaline, I purchased two hunkers in my last order from Africa.  The following is there stony.   They maybe a bit stranger than most, but not beyond reasonable limits.

Regal purple weighs in at just less 100 carats and is ready to fight.

The inter net picture looks  rather like a purple/pink, but I don’t really trust the color on my screen.  I go more for the description and I try to nail down what purple is “regal” and all I really get is “royal”.  Oh, what the heck it doesn’t cost an arm and a leg like most decent tourmaline rough does today and it will be fun whatever the color.  (Still a really purple tourmaline would be great!)

When the hunker arrives I find a completely water worn piece that looks pretty flawed and an obvious place to make the first cut.  It is a pretty straight line of damage that is bad enough to make one side of the flaw lighter color than the other bigger side of the rough.  And with rough like this, I only bother to find the place for the first cut before diving in.  I am not too happy in hitting the line with my first cut, but it lets me see much more clearly what is in the heart of this tourmaline.  And news is out that the rough has a fine vivid pink color with a significant overtone of purple, but it is not a purple in my book.  While the heart of this tourmaline has been pretty well been crushed by nature.  Still there is good transparency in the remain cells of cuttable tourmaline and the work goes on.  As I have said, cuttable includes imperfections and with pink that is a much more common occurrence then greens along with other colors.

Now the second cut is more on the mark and I find that the corners of the more or less triangular pebble are probably the best spots in the pebble.  Two of them will probably cut the biggest stones and then they will probably only come in at a couple of carats each, at most.  But their vivid, well saturated color in a fine medium tone level, even in the small pieces I am producing is mouth watering.  After a lot of sawing I have maybe a dozen pieces of sawed chunks that may make gemstones.  None of them will be clean if I go for maximum weight retention, which is what I plan to do at this stage in the hunt.

After grinding a few preforms I pick one of the bigger pieces and dop it.  I am using a wax that is new to me and seems to be completely made of shellac.  It is strong, but has a mixed record of holding on to the preforms.  I therefor ground a head, made of the wax, on a dop stick and used epoxy to attach the preform to the wax head on the dop stick.   Besides holding the preform well, the level base of wax helps me keep the preform perpendicular to the axis of the dop stick.  This is very important in getting a decent yield out of small thin pieces along with a good centering effort.

With this preform, I had lots of depth, at least to start.  The first set back was a really nasty ditch in one side of the preform as I ground the culet.  It did not go all the way threw, but none of it could be left in a quality stone.  I lost some depth, more than I expected, but the cutting and polishing went smoothly.  Still the few flaws I ran into were of the type that fall apart into a visible break in the surface and I work hard not to include in a gemstone for structural and aesthetic reasons.  I could also see that the nascent crown was more included than I had hope and I had much less depth to work with than I had hoped for.

After finishing the pavilion and checking out the crown, things did not look promising.   I had left more included material under the nascent table in the preform than usual.  As I have said, I was prepared for an included stone, but not one as broken as the top of this gemstone turned out to be.  All the flaws were of the break apart type and as I dropped the angles of the mains I finally realized that there was no saving this 9mm round from a complete regrind.   And so I took her down to less than a mm from the height of where the pavilion met the girdle.  Now that is a thin crown!  And the stone was still not clean, but I figured that by the time I centered and redopped the stone the remaining flaws would not be a problem.  (wishful for thinking)

So I ground down the 9mm  round into a 7mm round and recut the pavilion.  I had had some minor breakage as I polished the original culet and that was removed in the regrind.  That was great because you can loose a culet with a problem like that, but I lost some more precious depth.  Well I had enough dept in the crown to use 40 degree mains, which are my favorite, but the nasty breaking flaw was still there and centered in one of the mains and extending under the table.  Not acceptable and so I drop the mains angle.   Testing each angle to see if the flaw was gone.  Finally at 30 degrees the devil was contained to a small spot in one of the mains.  Now I never expected to get a clean gemstone and the flaw was at last deemed to be insignificant and not distracting.  It certainly was not a threat to the gemstone anymore. Now a bit a playing with the angles of the star facets and break facets produced a fine quality standard round brilliant.  The flaw is still there, but it did not tear the surface of the main facet though it does mark it and is barely visible by eye.  A flawless stone would have been no stone at all worth mentioning.

I always take new gemstones for a walk in the world to see how they respond to different lights and this medium toned, vivid pink with an overtone of purple beauty, got the full treatment.  As expected she gets more or less purplish with the changing natural light, but she is always vivid and pink.  The best moment was when I showed my walking buddy, her bluish face and he was very enthusiastic about her polished figured and proud coloring.

A Violet Heart and Blue Green Girdle, 110 Plus Carat, Hunk.

The rough for this project was rather peculiar.  It was completely water worn and nothing had been done  to the chunk to reveal its inner truth.  It had a small area of thin rich green on the old crystal faces, that was so thin that it probably will not be useful and a pale gray blue/pink center without any residual crystal faces that had deep blunt pits in it.  (sort of like a cauliflower head, but with a looser head than a tight creamy one.)  There were not many really defined flaws in the heart, but the thin green was mostly flawed.  There were indications of differences in transparency that really did not help me place the first cut, so I cut threw one of the deep blunt pits.  At least I would not have to grind it out of a preform now.  Well I now had two good sized pieces and the one I chose to work on had an end that some kind of flaws that looked rather like reflections off straws.    They were not growth tubes, but rather ghost-like ripples.  I split the piece and worked on the cleaner part that was almost without the ripples and just a few conventional flaws.  Besides being cleaner, it also made up into a pretty well balanced bi-color.  Yes the violet of the sale turned out to be a bi color.

It was still a good sized piece and I had to get out an old aggressive lap to make her shed the weight.   Finally my significant emerald cut was ready to be polished.  And it polished very fast, but it was almost too easy to move the facets which caused me to have to square them again.  The keel did not chip and after a successful polishing effort, I transferred the stone.  It was going to be a decent stone as far as cleanliness went, but the color was so grayed and pale that only a ghost of a pink color floated before my eyes.  Now it is unfair to judge with the stone being doped, but this was going to be one pale stone.

I finished the stone without any problems and after cleaning, the search for her color began.  Yes it was practically a search, but under moderate to lower light conditions I can see pink flashes in the grayed blue world.  A blue that in the end was so grayed that is could be just called gray.  It is a noticeable bi-color,  but when the 7 carat emerald cut is faced with a bright light like the sun it washes out into a gray, completely.  It is different enough to be interesting, but I think the rough was not investigated by the dealer more because of its pale nature than flaw structure.  This is support by the gemstone having acceptable crystal quality and the noticeable flaws being relatively few.

So there are two very different hunks of tourmaline that are graded the same, but are worlds apart.  I think the small vivid pink with a touch of purple will be the most satisfying in the end.  That piece, with a lot of work, will probably be worth the price.  The second pale piece of rough is more interesting because it is different.   A difference that mostly disappeared in cutting and it just does not have a great amount of color interest.  Still it broadens the vast world of distinctive tourmalines out there to be seen.

Bruce

 

 

 

 

 

Bruce

 

 

 

 

 

 

 

 

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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