What will 65 carats of included hot vibrant pink make?

briannortanpink148

The trip of discovery has begun.  I had to use my facet saw to cut the ends and take out a bad feather from the water worn piece of rough that had almost been completely cobbled.  Whenever I need to use the saw I don’t get an exceptional yeild from the rough.  This was on top of needing to grind out some significant naturals.  But I was still able to get an oval that is about 11.6 mm by 17.5 mm.  The oval will have a nice deep crown and a substantial girdle because the piece is still moderately included.

The exciting thing about the work in progress is it tone level and color.  I have a small included sample of a tourmaline they call “strawberry” from Afghanistan that sits on my kitchen window sill (the land of lost tourmaline).  It has the most intense vivid pink I have ever seen in tourmaline.  The oval to be may not have as high a tone level as strawberry, but it size should help to make up for that, and the work in progress has the same color as the “Strawberry”, I got years ago from Afghanistan.  Wow.

The next step is to polish the pavilion and I hope that the culet facets do not chip too much.  Hot pink tourmaline like this can be difficult.

There was some chipping on the culet and a small amount of undercutting on some facets, but the pavilion is now very bright and finished.  It is always interesting/disappointing/ exciting to see the garden of natures that are finally revealed as you polish an included gemstone.  The crystal between the inclusions in this hot pink tourmaline is exceptionally good.  It made the reflective flaws sparkle in the morning light.  The pink color keeps me excited.

I decided to make a stepped facet crown to be able to control the crown’s thickness easier.  I left myself a good amount of stone so I have better flexibility in grinding the table.  Today I started out with a round of 55 degree girdle facets to orient the transferred gemstone.  I left a thick girdle so I can recut the facets as needed without pushing the girdle.  I reground the girdle row of step cut facets several times, in an effort to remove all of white opaque flaws around a weak corner of the oval.   At forty degrees I was able to eliminate the white opaque inclusions, but there are still some flaws.  They should be minor.   I like forty degrees for the girdle angle and I can live with the flaws, so it was off to regrind the the table to a decent ratio of the width of the oval.   As I was grinding the table facet, a potential disaster struck.  An unknown weakness in the stone began to break the surface of the ground table facet.  It appeared to be at a low angle to the table facet and I could not see any extension of it into the heart of the gemstone.  Still it refused to stop breaking and making a quite visible river valley in the table, I wanted to stop cutting.  Finally I had to use my finest finishing lap more than I wanted to and while the flaw is still there, it is much reduced and is not breaking anymore.  Adjusting the second row of facets to 25 degrees and about one third of the depths of the crown, I am ready to polish the table.  I think that there is a good change that the limited area that is still broken will not break anymore, but only time will tell.  I am hoping for a bit of good luck and I will recut the crown if I have to.

The table polished nicely, but a couple of wounds open up that can not be polished out and I will try again after I regrind the table.  It is not unusual to grind the table at least a couple of times before I am satisfied with the polish.

I have reached a decision after a regrind and hours of polishing, that the table is done.  It is a tough decision because of the flawed nature of the gemstone.  The regrind did not produce a less flawed surface, but careful polishing has limited the amount of breakage around the flaws that penetrate the surface.  Still the breakage is noticeable by eye, but there is nothing more I can do about that.  The really difficult feature of the table is two scratches the came from polishing, but can not be practically removed by polishing.  If the gemstone was pure, I would regrind the table, but there is a flaw, that is still buried in the gemstone, that is getting dangerously close to the surface.   To open that flaw would be very negative and there is no certainty that I could get a better finished on the included table with another regrind.  With the much more noticeable breakage around existing flaws, than the scratches and a fine flat finish on the table, it is time to accept the limitations of the gemstone.  So it is on to the step facets around the table.  The principle effort will be to get good meets for the small facets that should polish easily.

The stone is done, but it did not go down that easily.  I had breakage problems around a flaw, along with under cutting and a healthy mistake in polishing a facet that required time to fix.  The breakage was related to the undercutting since I use pressure and slow movement to try and minimized the rippling effect of undercutting.  It is not an unusual problem with pink stones that have facets that are close to the c axis.  Fortunately the table was not exactly on the c axis.  It is hard to tell the c axis in this stone since it is NOT dichroic.  Dichroism is not a diagnostic feature of tourmaline, it depends on the chromophore’s interaction with the structure of tourmaline.  Therefor it is not intrinsic.  The heavier pressure caused a flaw to fail like the one on the table and it continued to fail with normal pressure.  In my frustration with undercutting, which can be hit and miss, even away from the c axis with my polishing method, I made a non standard facet move and ended up over polishing one of the 25 degree steep facets.  It took time and a practiced touch to correct, but it is not noticeable to me now.  The breakage around the flaw was reduced, but not eliminated and now it is time to talk about the bottom line.  The stone’s overall impression and beauty.

This is a beautiful gemstone.  Nothing could be done to get anything out of the rough without flaws, but the stone’s crystal is excellent and with a fine polish the included stone is still very bright.  It’s color and tone is excellent and I am reminded of pink hard candy.  Frankly even the flaw’s flash are so crisp that they don’t bother me too much threw the pink power.  It weights about 8 carats for a yeild of about 12 per cent.  This is less than half of what I would expect from a “normal” piece of relatively un-flawed material.  It is not exceptional when it comes to included material and certainly makes the material more expensive than the rather low price per carat indicates.  Still I am not sure that I could even get a hold of a “flawless” piece of tourmaline with this vivid a color and fine tone level in the present rough market.

And so the quest goes on for beauty in tourmaline.  I think that I won this one overall, but it will never suit the perfectionist.  The stone was certainly much more of a challenge and effort than any comparable piece of “flawless” tourmaline rough.  It makes the victory so much sweeter, even if it is not a very good way to maximize my monetary return from time spent cutting.  I will never be commercial.

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.

This entry was posted in Cutting Tourmaline, Personal Stories, Pink and tagged , . Bookmark the permalink.

Leave a Reply