BOGx_USFG - FULL Version Available

BOG for the USFG Hex Tilt Competition

A number of users have asked me whether BOG could help with the upcoming USFG hex design competition. The initial answer was no, since the competition rules require GemRayX, not GemRay, to evaluate the design. The major difference between GemRay and GemRayX is the inclusion of a head shadow in the "X" version (further information appears on Robert Strickland's website at

BOG was developed before GemRayX was publicly available, and it uses a different approach to the head shadow issue (see here for details). Nevertheless, programs like BOG are ideally suited to the type of judging criteria established for the hex tilt contest. Therefore, over the holidays, I modified BOG somewhat to produce a new version, called BOGx_USFG, that is tailored to the USFG competition.

To keep things fair, I have disabled the Optimize and Merit Function Map in this version (BOGx_USFGd). Nevertheless, the PlayPen option is ideal for tweaking, comparing, and scoring gem designs. See the screenshot below.

The image at left shows the PlayPen in BOG_USFG.

The user has already evaluated the hexpo8.gem design (lower blue panels labelled Ref). It has a total ISO brightness of 343.3 with the nominal pavilion and crown angles (40.2 and 39).

By clicking the Raytrace then MakeRef buttons, the user stored hexpo8.gem in this reference channel. Then, he selected a new file (Robert Strickland's excellent flyeye.gem from the USFG yahoo site) by clicking the file button to the left of the filenames). The screenshot captures BOGx_USFG just as it was about to evaluate the gem at 20 degrees tilt.

You can tweak the pavilion and crown angles, compare multiple designs, and automatically calculate the USFG score.

I will release the full version, including Optimization, after the contest closes on the 10th of January. With a minute or two of effort, the full version of BOGx_USFG managed to improve every one of the half dozen or so posted competition designs that I tried.

Download, Installation, and Operating Instructions

Download Full Version

Click on the link at left to download a zip file containing the program (approx. 150 kB).

If you already have the original BOG running on your system, simply unzip the file in a working directory and double click it.

If you have not yet tried the original BOG, you may need some additional Windows support files.The easiest way to proceed is to install the original BOG, then the USFG version. Follow this link for full BOG download and installation instructions.

You will also need a copy of GemRayX, which is available for free download at

BOGx_USFG operation is essentially identical to BOG, with the following exceptions:

1. Optimization and Merit Function Map are disabled until the new version appears on January 10 - Full Version Now Available
2. The "Evaluate Tilt Performance" option in the PlayPen has been replaced with the USFG contest criteria
3. The "Tilt Performance Plot" has been replaced with the numerical listing of ISO values (see screenshot).
4. Sharp-eyed BOG users may notice a few minor improvements associated with the upcoming v. 1.1 release

If you are unfamiliar with BOG, there is a complete tutorial available in the BOG download or online at this link.

Don't forget to set the gem material to topaz!

Have fun, and good luck!

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Web page maintained by Tom Herbst. Last modified 12-Jan-2003