A diagnostic map that colors every pixel on the crown according to the hemisphere angle of the light ray it returns: Red (15°–45°) for direct overhead brilliance, Blue (0°–15°) for viewer head-shadow contrast, Green (45°–90°) for low horizon light, and Black for light leakage.
Break Facets
Facets sitting immediately adjacent to the girdle (e.g., P2 on the Pavilion or C1 on the Crown) that level out the girdle line and split main facets into smaller virtual facets.
CAM (Centerpoint Angle Method)
A preforming technique where temporary pavilion facets (PF1, PF2…) are cut to a single central point (cp()) at calculated angles, followed by 90° vertical girdle cuts (G1, G2…) meeting mp(PFk) to form an exact non-round outline.
Critical Angle ()
The minimum internal angle of incidence required for a light ray to undergo Total Internal Reflection (TIR) instead of leaking out the back of the pavilion.
Crown (C)
The upper dome of the gemstone above the girdle.
Culet (cp())
The bottom apex where the lowest Pavilion facets meet at a point.
Dispersion (Fire)
The splitting of white light into spectral rainbow flashes caused by wavelength-dependent refractive index variation.
Dop
The metal rod to which the rough gemstone crystal is attached during cutting.
FCI (Faceting Complexity Index)
ProFacet’s 0–100 difficulty score computed from total facet count, tier count, acute angle changes, and delicate meetpoint tolerances.
Girdle (G)
The 90° vertical perimeter belt separating the Pavilion from the Crown.
Index Gear (96)
A toothed wheel on the faceting quill that divides the 360° circle into discrete stops (e.g., 96 teeth = 3.75° per tooth).
Main Facets
The primary structural facets of the Pavilion (P1) or Crown (C2 / bezel facets) that drive primary light reflection and refraction.
Meetpoint (mp())
A 3D vertex where three or more facet planes intersect at a single sharp corner.
Pavilion (P)
The conical bottom section of the gemstone below the girdle, designed to reflect light upward via Total Internal Reflection.
Scintillation
The dynamic interplay of bright and dark flashes (virtual facets turning on and off) as the gemstone, light source, or viewer moves.
Star Facets
Shallow triangular facets surrounding the flat Table (T) on the upper Crown (e.g., C3).
Table (T)
The flat 0.0° horizontal facet at the very top of the Crown.
TIR (Total Internal Reflection)
100% mirror-like reflection of light inside a gemstone when a ray strikes an internal facet at an angle steeper than the critical angle (θc).
Windowing
Undesirable light leakage through the bottom of the pavilion when pavilion facets are cut too shallow (< θc), creating a dead, see-through zone under the table.
You referenced a tier in mp(TierX) before TierX was cut (check your top-to-bottom tier order!), or
An earlier tier cut so deeply that it completely ground away the tier you are trying to meet, or
On a Pavilion break tier (P2), your angle is shallower than P1 (cp()) instead of steeper than P1.
Fix: Ensure Pavilion tiers that meet cp() (P1) are slightly shallower (e.g. 41.5°) than outer Pavilion break tiers meeting gp() (P2 at 43.0°), and verify in Palette mode with Facet Info turned on that the target tier exists on the mesh.
Cause: You forgot to include + girdle on the first Crown tier that meets the Pavilion girdle (C1 0 @ 42.0 : gp() + girdle x8 m 3 or C1 3 @ 42.0 : gp() + girdle xx8), or an optimization range (+/-) allowed a Crown tier to cut deeper than the girdle.
Fix: Click +girdle on your first Crown tier, and check Protect Girdle (Enforce closed girdle) in the GPU Optimizer!