Using ASET Scopes

“See the cut quality of your diamond before you buy”






ASET Scope – The Best Tool for Fancy Shapes Cut Grading



is blocked by the observer (some blue adds contrast)


is best: most light comes from above –from the ceiling


is OK; it is reflected and from windows, but red is better


shows how much leakage is present (bad, especially when the leakage is adjacent to blue; this often results in a large dark zone in normal lighting)
ASET Daylight Movie

ASET Daylight Movie – 0 to 10 degrees

  • AGS quantify’s blue, red, green and leakage with its Performance Grading Software™ in 1° steps of tilt from 0° to 45°
  • 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 leakage – for a lot, or large zones
  • Downgrade for mostly green & little red
  • Downgrade for too much or too little blue
DC_0_degrees Daylight_0_degrees
DC_5degrees Daylight_5degrees
DC_10degrees Daylight_10degrees
DC_15degrees Daylight_15degrees


Our Recommendations in using ASET Scope

  • 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

For buying fancy cut stones, we recommend initial face up selection with an Ideal-scope –  followed by final selection using your ASET

View our ASET Reference Chart with movies online