Green Shield Cut rarer than you might think.

 

Great Green Shield Cut This gemstones has a great cut and all the physical properties of a beautiful high quality gemstone. I also like it. It weighs 1.75 carats.

Green in all its shades is one of the most common colors in the world of tourmaline.  Only pinks might compete with green as production shifts between locations during different years.  Yet there are very few nice green shield cuts in the collection.  This is despite the fact that I like shield cuts (one of the few “modern” cuts I use) and many tourmaline crystals have a triangular cross section.  So now comes the negative part.  Many green tourmaline have “closed or partial closed ends”.  Having a closed end means that the crystals  transparency down the principle axis of the crystal (usually the long dimension of the pencil like crystal) is very poor.  So dark and dense that only emerald cuts with steep end angles (70 degrees plus) can effectively produce an acceptable gemstone. Even if the principle axis is open enough to produce a nice gemstone with its table perpendicular to the c axis, a great deal of the green tourmaline rough is usually found/produced in sections that are not the right depth to produce a shield cut or even a round with a good yield.  Cutting shield cut with its table parallel to the principle axis would also be an  inefficient use of the rough in most cases. (I am talking about Elbaite, which is the most common tourmaline species used in gemstones and not chrome tourmaline which is a completely different species and left for another post)

So the gemstones displayed above is a really nice green with great color, saturation and tone level.  It is also clean, which the most common level of cleanliness with greens and a nice size too.  It is also bright and flashy from the cut and good crystal and all of this makes it a very nice addition to the collection.

 

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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