How to Use IS & ASET

Reference Chart - IS

Reference Chart - ASET

Light Return & Shadow

Mounted Diamonds

Fancy Shapes - IS & ASET

Symmetry

Ideal-Scope Test

Using Tweezers
 
HCA CUT CALCULATOR
(free)

USING IDEAL-SCOPE
ABOUT

RESELLERS/AGENTS
NEWSLETTERS

 
 
  Print this Reference Chart
     
ASET Chart
       
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Poor
       
excellent
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Daylight Video vs DiamCalc Video    
Excellent
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Click to download the respective Gem or DiamCalc Files
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Very Good
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Download this ASET Reference as a powerpoint (file size: 9MB).
 
 
ASET Scope - the best tool for fancy shape cut grading.
ASET Pic
ASET Light
ASET shows where a diamond gathers its light.
Blue
is blocked by the observer (some blue adds contrast)
Red
is best: most light comes from above –from the ceiling
Green
is OK; it is reflected and from windows, but red is better
White
shows how much leakage is present (bad, especially when the leakage is adjacent to blue; when you will see a large dead dark zone in normal lighting)
   
  • Face-up (0°) is weighted much more than 45°
  • We recommend tilting the stone to about 15° while looking at it through your ASET scope
  • ‘Face Up’ counts the most
  • Downgrade alot of leakage, or large areas
  • Downgrade for mostly green & little red
  • Downgrade for too much or too little blue

 

 

 

 

 
DC 0 degree 0 degrees
Daylight 0 degree
DC 5 degrees
5 degrees
Daylight 5 degrees
DC 10 degrees
10 degrees
Daylight 10 degrees
DC 15 degrees
15 degrees
Daylight 15 degrees
   
Using ASET
  • We prefer to back light diamonds
  • Comparing brightness of colors is easier
  • Seeing leakage makes it easier to discern good from poor stones
   
  • The best way to use ASET is rock stones from side to side as shown on the movies
  • We recommend you ‘weight’ 50% from the face up view and 50% from rocking views
  • While not ‘scientific’, with some practice you can identify stones that look bad when tilted
Excellent
Daylight Movie - Excellent Cut
Fair
Daylight movie - Fair
 

Back lighting makes it easier to discern good from poor stones:

  • using back light makes comparing color brightness more effective

  • large leakage zones are easier to identify
For buying fancy cut stones, we recommend initial face up selection with an ideal-scope - followed by final selection using your ASET scope.
Selection Process