The Standard Round Brilliant and Some Common Variations
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| Standard Round Brilliant “Classic” – GemCad Derived Renderings by Bob Keller bkeller@rockhounds.com | |
|---|---|
| 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{6303d0458f78485017e3ff509f07809060e27c7680a1c87bf8e331bc046fca94} ISO = 46.5{6303d0458f78485017e3ff509f07809060e27c7680a1c87bf8e331bc046fca94} |
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| 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. | |||
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