Online Faceting Designs & Diagrams: Gram Princess
Gram Princess by Jeff R. Graham
Gram Princess – Cutting Remarks
Shown at left is a 12mm ~ 5.61 carat “Gram Princess” cut from flawless Brazil Citrine by Jeff Graham.
This can be cut in refractive indexes 1.62 to 1.93 with no changes. If you want to cut this in Quartz (70%), just add two (2) degrees to all of the pavilion tiers. No changes on the crown… The crown can also be raised 4 to 6 degrees with out changing the light return much, on any of the higher refractive indexes. Changing the angle of the C3 tier by a degree or so, up or down will change the overall size of the table quite a bit. It is a good trick to use if your stone needs a little more or less area when you are cutting it… This is not especially hard to cut, but the meets on the corners of the pavilion are tight and it is easy to cut through them.
According to Eric Bruton FGA, the author of “Diamonds” the Princess cut was introduced by “A. Nagy” a London cutter in 1960 as an economical cut for flat diamond crystals (p216).
People ask me for a “Princess” cut quite often. But the “Princess” diamond cut does not lend itself to being cut in the lower refractive indexes of colored stones very well. So I decided to redo the entire cut for colored stones, the original concept of this design is not mine. The “Princess” was originally designed for shallow diamond rough many years ago, they were trying to find a way to use some odd rough…
I have made quite a few changes to get a design that will cut well in colored stones, but still have the over all feel of a “Princess” cut. This design is not a traditional “Princess” cut, which is why I named it the “Gram Princess”. I want people to be sure and know that this is a redesign/recalculation (by me) of the original and that I made changes. This design will work very well in almost any material, I think it is particularly good for saturated stones. I also like it in a Zircon and Sapphires.
Something else of interest, look at the ray trace (on the bottom of this page). Notice the dark areas in the four (4) corners of the design. These areas are actually trapping light rays, which is why they look dark in the ray trace (the ray trace loses track of them and does not count them in the brightness figure, at least I do not think it does…).
Now look at the picture of the cut stone. See any thing interesting? These areas are actually returning light and the color of them actually looks a little more intense than the rest of the stone. That is because of the trapped light rays. The light ray trace is a good indication of the overall look of the stone, but it is not perfect. I have noticed this phenomenon in other designs that I have published (you may have seen a comment that I made, but did not really know what I meant). But this picture and design really shows off what is happening well…
Enjoy cutting your “Gram Princess”… Drop me an email to let me know your results and what you’ve cut, or feel free to inquire if you have any questions or need some help regarding this design.
Random – Cosine – ISO
Detailed faceting instructions by Jeff Graham available at The Rock Peddler