How to Cut a Classic Portuguese

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PinkDiamond
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How to Cut a Classic Portuguese

Post by PinkDiamond »

After all this time, the number of threads in this category will finally double today, with 2 threads provided by Jeff Graham being added, proving that in some cases, doubling in size in one day can be a good thing. :lol:

This is a beautiful cut, and Jeff Graham modified it and made it easier, with fewer facets, and he goes through the steps for you, with pics. You'll need a good size chunk of rough to cut it, and he recommends lighter material, saying the cut darkens the stone. If anyone tries it, let us know how it went, and do show us your stone. This is from the International Gem Society's newsletter. Enjoy! :)

How to Cut a Classic Portuguese
by Jeff R. Graham

"The classic Portuguese (Vargas) cut has 161 facets on it. Because of the depth that is needed to cut that many tiers and facets the stone/design is pretty deep. The depth of the original limits the material that will work well in it to basically refractive indexes 1.76 and higher.

The lower indexes just do not perform well in the old style Portuguese cut because of the depth needed to cut the design. In lower refractive indexes there is always a fairly large dead area in the stone (either in the center or out around the crown, depending on the angles used). With this in mind I went to the drawing board (or computer in my case) to see if I could come up with a design that would have the style and flavor of the old cut and yet have a good performance in lower refractive indexes.

What I came up with is the “Simple Portuguese”. It has 145 facets and at first glance most people will mistake it for the original. The only difference is one less tier on the pavilion and some tweaking so that the star burst on the pavilion will show thorough the table. Frankly a few less facets is a good idea, it is difficulty to find natural rough that is large enough to cut this design.

Image

Material: Tourmaline
Type: Rubellite
Locality: Africa
Hardness: 7 good for almost any jewelry application
Design: Simple Portuguese (designed by Jeff R. Graham – Simple Portuguese)
Cut By: Jeff R. Graham
Dimensions: 14mm x 9.2 deep
Clarity: VVS
Weight: 10.30 carats

Cutting the Simple or Classic Portuguese

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Rubellite Tourmaline rough

This is a picture of the rough piece of Nigerian Tourmaline that I started with. As you can see this piece of Rubellite is about medium saturation. I really recommend that people use a light to pale piece of material, this design does darken a bit and unless you are very experienced at judging rough and how it will finish. There is a good chance that you will end up with your stone being on the dark side.

I personally think this designs needs to be in a light stone so that all of the facets and their inter play can be seen in the finished gemstone. It is a lot of work to cut all of these facets, if you cannot see them in the finished stone well.

Grind a Flat Spot

The first thing that you need to do is identify any flaws or bad places in your rough. I generally try to hand grind any of them out that I can before I dop. The heat from the dopping process, while not hot (unless you goof), does tent to aggravate cracks if they are there, in the rough.

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Grind a flat spot

After you have the flaws out (and any preform shaping that you may want to do), be sure and grind a nice flat spot where you want to put the table. Hint: If you are not sure how clean your rough is. Cut the flat spot for the dopping/table area and fine cut it so you can look into the center of the rough for any flaws that might be there.

Choose a Dop

This sounds like an easy thing to do, but a lot of new cutters make the mistake of picking a larger dop and then as they cut their stone and it gets smaller, they find that the dop they used is too large.

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Tourmaline rough and dop

The best thing to do is pick a dop that about one size ... "

https://www.gemsociety.org/article/cut- ... e_increase
PinkDiamond
ISG Registered Gemologist


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