How to Cut a Portuguese Gem Design
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.
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
Weight: 10.30 carats
Cutting the Simple Portuguese
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.
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.
The best thing to do is pick a dop that about one size smaller than you think. Look at the picture above and you can see that the dop I used is not all that large. I prefer to use a little more wax (which can be cut off), than a larger dop.
I prefer to use red/brown wax but use whatever you like. Make sure that the dop and stone are well attached and that the rough is centered.
Dopping is really where you loose or gain weight in recovery, so take your time and get it right. As you can see this piece of rough had a couple of dings and bumps that I needed to work out on the girdle line.
The rough was not all that round, but by the time I got it evened out it actually yielded pretty well.
Rough in the P1 & P2(G)
First thing that I cut in is the P1 tier. Notice that I did not cut it to center point, to help save rough.
By roughing in the P1 and the P2(G) I can get a good idea of the finished dimensions of the stone.
I did not cut P1 to center point because when I come back and cut the P3 (and the rest of the pavilion tiers) they will center point. I can get away with this because this design is a round and none of the pavilion facets define/set the size of the girdle facets.
All of the facets cut to the same angle.
Rough in & Fine cut P1, P2(G), P3, P4
As you can see when I roughed in the P3 tier it is almost center point. It is time to fine cut all of the tiers that I have cut to this point (P1, P2(G), P3).
At this stage I check again for any flaws. Because the rough/facets are cut fine enough for me to be able to see into the rough all the way around easily. By spotting a problem now, if there is one, I can save myself a lot of work later.
Fine cut in the P4 and P5 tiers.
Polishing Girdle and P1-P5
After Fine cutting the P5 tier in start polishing. I used a tin lap (scored) with aluminia oxide to polish this stone. I always polish the girdle first, then P1 – P5.
Polishing all of the facets on this design is not hard, but it does take a lot of work. When polishing P4 and P5 the points tend to be small and it is easy to over cut/polish if you are not careful.
When I pick a cone dop for the transfer, I try to get one that is almost as wide as the stone, but not quite.
Rough in C1 & Fine cut C1, C2, C3
I generally use a fairly coarse lap (my worn 260) to rough in the C1 tier and get the cheater setting (if needed) close after transfer. Then I switch to a fine lap (my worn 1200 steel) for doing any cheater tweaking that maybe needed.
Then I fine cut in all of the crown tiers.
Fine cut C4 and Table
Fine cut in the C4 tier, be careful it will cut fast.
Next, I usually cut in the table… I find that cutting in the table at this point makes the star facets (C4) much easier to meet up and it is just easier for me.
Note: I polish the table, while I still have the setting I used to cut it in with, saves time and fishing around.
Polish the rest of the stone
I polish in the C2, C3, and C4 tiers after I have already polished the table. You can leave the table for last if you want to. But I find that it is easier to make all of the star facets point up when I have the table already established.
Tip: I leave the table just barely short of meeting the star facets (C4). That way I can pull the star facets slightly towards the table when I polish them, keeping the point on the C3 tier sharp.
Have fun cutting my “Simple Portuguese” and let me know how you do.