|Octoburst - designed by Steve Corman firstname.lastname@example.org|
|Angles for R.I. = Angles for R.I. = 1.74||65 facets + 8 facets on girdle = 73|
|8-fold, mirror-image symmetry||96 index|
|L/W = 1.000 T/W = 0.507 T/L = 0.507||P/W = 0.446 C/W = 0.163|
|H/W = (P+C)/W+0.02 = 0.683||P/H = 0.701 C/H = 0.269|
|Vol./W^3 = 0.255||Brightness at 10 degrees tilt for RI = 1.74
COS = 71.7 ISO = 82.1
|1||56.00||96-12-24-36-48-60-72-84||Cut to level girdle|
|3||40.00||04-08-16-20-28-32-40-44-52-56-64-68-76-80-88-92||Meet 1-2. Cuts very fast! Use slow speed or stationary lap.|
|c||30.21||96-12-24-36-48-60-72-84||No meet. Cut to consistent depth.|
|00.00||Table||Meet points of b facets formed by c facets|
I named this cut Octoburst after the the sunburst pattern in the pavilion. It is very simple, 3 steps each for the crown & pavilion. It has a small number of total facets but the finished stone has a lot of sparkle due to the placement of the small ones. According to Gemframe, it has average ISO brightness of 82.1% over a 10 degree tilt (at RI = 1.74).
Note on crown step c: The depth of this cut is not crucial. The depth shown in the diagram gives a 50% table. A deeper c cut will enlarge the table, but doing this too much shrinks the b facets and decreases the sparkle of the stone.
Editor's note: If you are cutting quartz (RI = 1.54), you should increase the angles for P3 and P2 as the pavilion #3 facets are below the critial angle for quartz.
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© Bob's Rock Shop Bob Keller