Famous Diamond Replicas in CZ
By Scott Sucher
Advanced faceting project.

Famous diamond replicas cut in CZ by Scott Sucher. Top row: Tiffany, Cullinan I, Cullinan II Second row: Florentine, Cullinan IV, Cullinan III, Pasha. Third row: Dudley, Hope, Sancy Fourth row: Cullinan VI, Dresden, Cullinan VII Bottom row: Cullinan VIII, Cullinan V, Cullinan IX. Photo: © Jeff Scovil

This is the first of several articles on the cutting of famous diamond replicas in cubic zirconia. The instructions originally ran in Lapidary Journal back in the '60s, and while I have actually cut 16 of them, I can only find confirmation that my information is correct for six (the Hope, Cullinan I (see page 56) and II, Sancy, Florentine, and Tiffany). The other replicas, while definitely in the ballpark, are not up to my usual standards - but reader interest has been so great that I will share my instructions for these as well.

Please keep in mind that I cut these replicas 15 years ago. I will gladly share any information about both my successes and failures and welcome ideas from other cutters. However, remember the timeframe. The availability of CZ rough has probably changed. Computer programs that now can assist cutters didn't exist then. Laps, grits, and other tools have definitely changed.

I cannot emphasize enough that anyone who decides to cut a replica should do his or her own research to ensure cutting a perfect replica. However, the only way to cut a perfect replica is to have the original cutters' instructions. I have attempted to adhere to the original dimensions, and at the same time be true to the facet pattern appearance. A slight deviation in angles or settings has a dramatic effect on the finished stone. As such, unless the original instructions are followed, the best anyone can do is only an approximation. To this end, I have maintained the original shape of the outline and dimensions, but have had to use good judgment and common sense in calculating the depth of the pavilion, crown, or total depth. This also changes total weight, which is to me a good standard for evaluating how close the final stone is to the actual one. These are also the criteria I used when determining that I could only give instructions for six replicas with any authority.

Photo of diamond (my reference was Famous Diamonds by Ian Balfour) Accurate description or drawing of diamond Separate drawings of the facet pattern (helpful but not absolutely necessary) Drawing paper Large piece of glass or fluorite Dop wax, dop stick Sequence of grits and laps, including 180-, 280-, and 600-grit laps Blank aluminum lap with loose 3,000-grit as a prepolish Crystalube Loose 100,000 grit on a tin/lead lap For information on supplies, please see the Annual Buyers' Directory. Always ask for the MSDS (Material Safety Data Sheet) for any materials you buy, which will give you reactivity, health hazard, and safe handling data.

Cutting famous diamond replicas is not for the faint of heart. Large CZ can be expensive (some of my rough cost over $300 for a single piece) and may be rare if manufacturers are not making it anymore. I waited about three years for the rough for the Florentine and the Cullinan I and II replicas to be produced. A mistake becomes not only expensive, but a lengthy wait can turn into a waste of time with just a second of inattentiveness.

Additionally, polishing large CZ takes a long time. I have tried many techniques. What works on one facet or stone may not work on another. It's like disciplining children, you have to adapt to the situation at hand and figure out what works. And yes, this can change dramatically very quickly. The smaller replicas took 10 hours on average from rough to the finished stone. The average size (100 carats plus) took about 40 hours. The Cullinan II took me 150 hours, and most of that was polishing time. Others may have more success, and I sure hope so, but be prepared mentally. Between the time spent doing research, cutting, and waiting for the large rough, my entire project took eight years. Patience and persistence are mandatory.

STEP 1.
Decide which stone to replicate. There are many I know about, and probably many I don't. The criteria I used for selection were:

• Known historical reference (Cullinans et al).
• Color. A yellow, green, blue, or pink diamond is rare. A large one is unique in the world (Hope, Dresden Green, Florentine, Tiffany). If I can get more information on their dimensions, I may cut replicas of the Nur Ul-Ain, Darya-I Nur, and the pink remnants of the Great Table diamond residing in the Iranian crown jewels.
• Shape. The more unusual, the better. The Shah Jahan, Shah, and Kasicki (or Spoonmaker) diamonds qualify in this category, but were ruled out by the next.
• The ability to locate a photo or accurate description to cut the replica. The 3 listed above are so unusually shaped that extensive measurements and photos are required, but have been impossible to find.

Unless one is fanatical, cutting all the famous diamonds is not possible due to time and money. I have also considered some to be redundant, as they share common characteristics (color, shape). The only difference is size. Once you've cut one cushion with 8-fold symmetry, you've pretty much exhausted the uniqueness, in my opinion.

STEP 2.
Locate an accurate description or drawing. A photo is best. This is required to adhere to the facet pattern. Is the girdle faceted or ground and polished? A photo will tell you all of this. Get as many dimensions as you can - height, width, length, depth of crown, and/or pavilion, size of culet facet, etc.

It's helpful if you can find separate drawings of the facet pattern. Although a photo is more accurate, you can use drawings to assist in determining settings and angles. In this case, put a piece of drawing paper over the photo and trace the crown facet pattern. Do the same for the pavilion. Since most stones are photographed face-up, internal reflection makes this process more difficult. I use this tracing, along with the photo, to guide me. A photo alone can be used, but when you are cutting the pavilion, you will constantly be trying to see through the reflections to get an accurate picture of pavilion facets unless you have made a line drawing.

Utilizing the drawings and dimensions, use cutter's judgment to decide symmetry and angles. Most antique diamonds use 8-fold symmetry, so the settings for the main facets are easy to determine. Be prepared to change settings and angles (from the standard) for the break facets. Again, use the photo as a guide. There's more than one combination of settings/angles to grind a break facet, but only one that makes it the correct size and shape.

STEP 3.
Knowledge of trigonometry assists in guesstimating main facet angles. If a stone is 15mm wide and 15mm deep, the angles are much steeper than one 15mm wide and 10mm deep. Don't go below the critical angle when cutting. This was the fatal flaw for my Dresden Green replica, although I adhered religiously to the pavilion depth.

STEP 4.
Once you've thoroughly analyzed the pattern and determined angles and settings, find a large piece of glass - or even fluorite - and cut a rough copy. (Glass and fluorite are readily available, and are much cheaper than using CZ.) The copy doesn't have to be polished. All you are trying to determine is whether or not your calculations are accurate. You will also discover any hidden pitfalls. I cannot stress the importance of this step enough.

STEP 5.
Now the real work begins. Use all the previous steps to cut the replica. Check your progress often. This part requires every bit of skill you can muster. Even though you may just be following directions verbatim, how your material is centered on the dop affects angular relationships. Cutting instructions are guidelines, not gospel.

Outstanding cutter's judgment is required. On Vargas' scale of cutting difficulty, most replicas are a 4 or 5. (I know what you're thinking, that the scale only goes to 3, but this is not sufficient due to the amount of judgment involved.) Now is the time for the sequence of grits and laps. All of them are the standard diamond-impregnated laps, unless otherwise noted.

STEP 6.
Use whatever you want to hog out the majority of excess material. I used a 180-grit lap. Leave a 3mm girdle with 2-3mm of excess material in all dimensions for the large stones, because this is just a roughing step. Smaller stones require less, but the exact amount depends on individual skills. Even if you're extremely experienced, I wouldn't get any closer than 1mm to the finished size, or smaller than a 1mm girdle.

Regardless of size, crudely shape the crown and pavilion, then use dop wax to attach the dop stick. Use whatever system you are comfortable with (epoxy, resin, etc.).

STEP 7.
Next, use 280-grit to refine the shape and put in the facets. I'm a “pavilion first” cutter, so I start by estimating the final stone size and shape by where the pavilion mains and breaks meet at the girdle. This requires fairly accurate judgment. A thick girdle and oversized dimensions from the previous step allow for a small amount of recutting if a mistake is made.

STEP 8.
Once you are satisfied that the facet placement will meet the final stone's dimensional requirements, use a blank aluminum lap with loose 3,000-grit as a prepolish with Crystalube as a carrier if the stone is small (such as Cullinan V through IX). If the stone is large, a standard 600-grit should be used, followed by transition to the 3,000-grit.

Caution: It is absolutely imperative that all scratches from the previous steps are removed. If not, you will spend an inordinate amount of time on a finer grit removing scratches from large facets. It will also make your facet placement more difficult by trying to get the meets perfect and estimating how far you need to grind to get the finished size and shape.

Hint: If the 3,000-grit starts to scratch, or it is not removing material (as evidenced by a semi-polished finish), put some Crystalube on a tissue and wipe it across the lap's surface to remove old grit and contaminants. Do this several times with fresh lubrication and clean tissues until the tissue is barely discolored. Recharge the lap with grit (about the amount that would fit on the head of a straight pin), then put clean Crystalube on the tissue and wipe the lap only once to distribute it.

STEP 9.
The final step is using loose 100,000 grit on a tin/lead lap. Use normal speed, but apply pressure directly proportionally to the surface area of the facet being polished. A light touch is required for small facets on small stones. Bear down as hard as you dare when polishing a large facet. (The Cullinan I table is the largest you will encounter.) Be patient, don't get careless, and watch the heat buildup so that the dop wax doesn't soften.

Scott Sucher is a retired Air Force instructor pilot who has been cutting stones for 25 years. His wife Karen teaches seventh and eighth grade science classes, and routinely uses his stone collections as “touchy-feely” examples for the lessons.