Standard Round Brilliant Classic
GemCad Derived Rendering by Bob Keller
Standard Round Brilliant "Classic" Angles for R.I. = 1.54 57 facets + 16 facets on girdle = 73 8-fold, mirror-image symmetry 96 index L/W = 1.000 T/W = 0.516 T/L = 0.516 P/W = 0.466 C/W = 0.218 H/W = (P+C)/W+0.02 = 0.704 P/H = 0.662 C/H = 0.309 Vol./W^3 = 0.236 Brightness at 0 degrees tilt for R.I. = 1.54
COS = 40.6% ISO = 46.5%
Pavilion pb 45.00 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 43.00 96-12-24-36-48-60-72-84 Cut to meet pb,g Crown cb 47.00 03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93 Cut to meet g - level girdle cm 42.00 96-12-24-36-48-60-72-84 Cut to meet cb,g s 27.00 06-18-30-42-54-66-78-90 Cut to meet cm,cb t 0.00 Table Cut to meet s,cm This Standard Round Brilliant is shown with proportions and angles typical of that recommended for quartz in the classic literature such as Long and Steele's. It has 8-fold symmetry, 8 pavilion main facets meeting at the culet, 16 pavilion break facets, 16 girdle facets, 16 crown break facets, 8 crown main facets, 8 star facets and 1 table facet which spans about 50 percent of the overall width at the girdle. Note that the height of the crown is approximately one-third of the overall height, and that the pavilion break facets extend approximately three-fifths of the distance from the girdle to the culet.
The SRB Classic Design File is available for GemCad users.