GemCad Derived Rendering by Bob Keller

SRB Variation with Vertically Split Mains | |
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Angles for R.I. = 1.54 | 73 facets + 16 facets on girdle = 89 |

8-fold, mirror-image symmetry | 96 index |

L/W = 1.000 T/W = 0.597 T/L = 0.597 P/W = 0.449 C/W = 0.157 | H/W = (P+C)/W+0.02 = 0.626 P/H = 0.717 C/H = 0.251 |

Vol./W^3 = 0.209 | Brightness at 0 degrees tilt for R.I. = 1.54
COS = 42.7% ISO = 56.8% |

Pavilion | |||
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pb | 44.50 | 03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93 | Cut to temporary center point |

g | 90.00 | 03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93 | Cut to meet pb |

pm | 42.00 | 01-11-13-23-25-35-37-47-49-59-61-71-73-83-85-95 | Cut to meet pb,g |

Crown | |||

cb | 42.00 | 03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93 | Cut to meet g - level girdle |

cm | 38.00 | 01-11-13-23-25-35-37-47-49-59-61-71-73-83-85-95 | Cut to meet cb,g |

s | 22.00 | 06-18-30-42-54-66-78-90 | Cut to meet cm,cb |

t | 0.00 | Table | Cut to meet s,cm |

This variation of the SRB doubles the number of main facets from 8 to 16 by splitting them vertically - instead of cutting 1 main facet at 96° as with the classic version, 2 main facets are cut at 95° and 1°, instead of 1 at 12°, 2 at 11° and 13° and so forth. The mains can be split on the pavilion only, crown only, or both. Adding more facets by splitting the mains increases the scintillation and is one way of adapting or scaling the SRB for use with larger stones. |