Cutting the "Le Coeur de la Mer II".
I stared at the stone in the movie so much I shall have to go back and see what happened to the people. Two stones were cut. The first yeilded 55.4 carats. An odd piece of trim from the 155 carat rough yeilded a smaller second stone of 22.8 carats.
The stone in the movie was a CZ, very simply cut with large facets, and for this reason I broke my rule and only placed two rows of crown facets. Because it was cut as a barion, the stone looks very "busy" as it is. I needed the color intensity to get the deep blue seen in the movie. Asprey's (London) made the prop, and later, the finished piece with a massive sapphire which was recently auctioned for the Pricess Diana charity.
The second smaller stone was cut with three rows of crown facets, and notched. It's brilliant and sparkly, but looks less like the stone in the movie. (Well, I thought so, anyway)Here:
Cutting tooling and materials: Preform cones and girdle outlines with nickel bonded 320 diamond. Facets cut on 600 nickel bonded diamond, followed by 5 micron on tin alloy, then 0-1 micron diamond on tin alloy, then 0.05 micron alumina on tin alloy.
To max yeild the rough, certain sequences were followed. First, I roughly sawed the shape and hand ground the preform cones for the pavilion and crown. The stone was dopped and the girdle outline cut. (In order not to waste much material, I had cut this stone wider than the aspect ratio of the stone in the movie). A cone for the pavilion was generated in freewheeling mode at 43 degrees. This allowed an early "preview" of the P/C ratio. I wanted a high crown because of the pendant use for the stone, keeping the depth for color and the carat weight up, but with good weight distribution for wearing. A 96 index gear was used. Cut 16 facets at 43 degrees, beginning at tooth zero. (The usual 0,6,12,18...) Now set the angle at 42.2 degrees and cut another 16 pavilion facets beginning at tooth 3. ( 3,9,12,18,...)
Set the angle at 66 degrees and establish a level girdle, allowing these barion facets to fall wherever they intersect the pavilion facets, judging the depth only by the girdle meets. The result will be perfectly symmetrical, if your girdle outline is. Polish the girdle facets.
Transfer. Cut 16 crown facets at the same indices which were used for the pavilion, 0,6,12,18, 24,30,36,42,48,54,60,66,72,78,84,90 at 44 degrees.
Cut another row (OF 13) at 36 degrees at 3,9,15,21,27,33,39, (skip 45 and 51 if you want a sharp point) ,57,63,69,75,81,87,93
After I had sawed and roughly ground the preform, I polished the table first and dopped to it. This is controversial, so do what you want. The reason I did was the table dimension was quite well defined in preforming, and polishing a table this size is much easier when one does not worry about rounded edges. The crown/table meets are sharp.
Have fun.
