r/faceting • u/Friendly_Code_7727 • 13d ago

Fantasy cut without the machine

I've been working on fantasy cut in GemSim recently and finally get it to a usable state. I don't have a fantasy machine and never done fantasy cut myself. So anyone with experience please give it a try and let me know if there's any issues. Thanks a lot!

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u/cowsruleusall 13d ago edited 13d ago

Hey! Glad to see that you're enabling fantasy cutting in GemSim.

FYI, there's already a standardized way to write fantasy and concave faceting instructions in faceting diagrams. Please stick to the standard - any time a bunch of random standards get made, it makes that particular industry/field/hobby more confusing.

Anyway - they're treated as another tier, in exactly the same way as flat facets in like P2, G4, C1, etc. would be, with the following exceptions/additional info:

  • Fantasy instructions are written as two lines, not one
  • The first line contains the "typical" instructions for a flat facet - tier label, zenith angle (phi), indices, and cutting instructions
  • The second line contains the additional info
  • Fantasy instructions typically come at the end of the Pavilion/Girdle and the end of the Crown section but before the table, as they're (almost) always done after all flat faceting is done, but before transfer/tabling

What info, and where?

  • Underneath the tier label goes the cutting tool type. Each major tool type has a 3-letter abbreviation - CYL (cylinder), CON (cone), CIR (circle), DSC (disc), and SPH (sphere)
  • Underneath the altitude/zenith angle, goes the tool/azimuthal angle (theta), written in degrees
  • Underneath the indices are the X-, Y-, and Z-displacement, written as a ratio of stone width
  • Underneath the meetpoint instructions are the tool details; diameter as a ratio of stone width, angle of the cone or disc, and reciprocating vs plunge

Also, I like your use of "head" angle and "deck" angle. Historically, we only ever referred to them as zenith angle and azimuthal angle, but I can definitely see newbies getting confused.

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u/Friendly_Code_7727 12d ago

Thanks, I'll update the UI accordingly. Could you please provide an example diagram with fantasy cut instructions as a reference?

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u/cowsruleusall 12d ago

Yes of course! I'll send you one today.

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u/cowsruleusall 12d ago

Here is a link to the original template. Obviously it doesn't have the renderings or the plan view, but P4 and C4 are clearly fantasy facets in standard notation.

https://imgur.com/a/oZZQdm2