How to Cut a Simple Portuguese Gem Design
Learn how to cut Jeff Graham’s Simple Portuguese gem design with this step-by-step photo guide. This modified classic works well for deep gems with low RIs.
5 Minute Read
IGS may receive customer referral fees from the companies listed in this page.Why?
How Does the Simple Portuguese Gem Design Differ from the Classic Portuguese?
Because of the depth of the classic Portuguese, it works well basically with gems of RI 1.76 and higher. With gems of lower RIs, the classic cut always has 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 keep the style and flavor of the old cut but still perform well with lower RI gems.
My modification, the Simple Portuguese, has 145 facets. At first glance, most people mistake it for the original. The only difference is one less tier on the pavilion and some tweaks, so that the star burst on the pavilion will show through the table. Frankly, a few less facets is a good idea, because it's difficult to find natural rough large enough for this design.
You can find cutting instructions for the Simple Portuguese gem design here.
Cutting the Simple Portuguese
This is a picture of the rough piece of Nigerian tourmaline that I cut. As you can see, this rubellite has about a medium saturation. I really recommend that people use a light to pale piece of material because this design does darken a bit. Unless you're very experienced at judging rough and how it will finish, there's a good chance your stone will end up on the dark side.
Personally, I think you need to cut the Simple Portuguese gem design in a light stone so that you'll see all the facets and their interplay in the finished gemstone. It's a lot of work to cut all these facets, if you can't see them well in the finished stone.
Grind a Flat Spot
The first thing you need to do is identify any flaws in your rough. Try to hand grind out any that you can before dopping. The heat from the dopping process, while not too hot (unless you good), does tend to aggravate cracks in the rough.
After you grind out the flaws (and do any preform shaping you may want), grind a nice flat spot where you want to put the table.
Hint: If you're not sure how clean your rough is, cut the flat spot for the dopping/table area and then fine cut it, so you can look into the center of the rough for any flaws.
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. Then, as they cut their stone and it gets smaller, they find their dop is too large.
The best thing to do is pick a dop about one size smaller than you think you might need. In the photo below, you can see that the dop I used isn't all that large. I prefer to use a little more wax (which can be cut off) rather than a larger dop.
I prefer to use red/brown wax, but use whatever you like. Make sure the dop and stone are well-attached and the rough is centered.
Dopping is really where you lose 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 wasn't all that round, but by the time I got it evened out it actually yielded pretty well.
Rough in the P1 & P2(G)
The first thing I cut in is the P1 tier. Notice that I didn't 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 stone's finished dimensions.
I didn't 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 the P3 and Fine Cut P1, P2(G), P3, P4, P5
As you can see, when I roughed in the P3 tier it's almost center point. It's time to fine cut all the tiers I've 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 to see into the rough all the way around easily. By spotting any problems now, I can save myself a lot of work later.
Fine cut in the P4 and P5 tiers.
Polishing Girdle (P2), P1, and P3-P5
Polishing all the facets on this design isn't hard, but it does take a lot of work. When polishing P4 and P5, the points tend to be small. If you're not careful, it's easy to over cut/polish.
When I pick a cone dop for the transfer, I try to get one that's almost as wide as the stone, but not quite.
Rough in C1 and 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 1,200 steel) for doing any needed cheater tweaking.
Next, I fine cut in all the crown tiers.
Fine Cut C4 and Table
Carefully, fine cut in the C4 tier. It'll 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. For me, it's just easier.
Note: I polish the table while I still have the setting I used to cut it in. This saves time and prevents fishing around.
Polish the Rest of the Stone
I polish in the C2, C3, and C4 tiers after I've already polished the table. You can leave the table for last if you want. However, I find it easier to make all 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 gem design.
Some Pointers on Selling Gemstones
Carving an Arizona Black Jade Pendant
Denatured Alcohol for Stones
OMNI Faceting Machine
Spurrite Value, Price, and Jewelry Information
Lapidary Technology Through the Ages: Laps and Polish
Why are Topaz and Citrine Gemstones Misidentified?
Identifying Garnets Simplified
When you join the IGS community, you get trusted diamond & gemstone information when you need it.
Get started with the International Gem Society’s free guide to gemstone identification. Join our weekly newsletter & get a free copy of the Gem ID Checklist!