Ideal Scope

Ideal Scope – Basics

The Ideal Scope is a cut quality assessment tool for round diamonds. Its translucent cone and magnifying lens create a structured light environment which reveal areas of brightness, leakage, and contrast when placed over a diamond.

Ideal Scope in Action

Ideal Scope Illustrated

Under bright jewelry store spotlights all diamonds look bright.

The real test for diamond beauty happens under normal and low lighting conditions. Depending on how it was cut, light entering a diamond from above will either reflect and come up to the viewer’s eyes as brightness or escape through the bottom as leakage or windowing, resulting in dark areas.

Ideal Scope Illustration

Ideal Scope Analysis

Seen in Ideal Scope, the most brilliant diamonds have abundant red areas (brightness) with minimal white or light pink areas (leakage) and a symmetrical pattern of black (contrast) which resembles a pointed star.

Ideal Scope Examples

The first four (left to right) would all receive the “Excellent” cut grade.

Ideal Scope Examples

  • Left example: This is the brightest stone (red areas) with minimal leakage (white) and balanced, symmetrical contrast (black).
  • Middle examples: Decreasing brightness (red areas). Increasing leakage (white). Decreasing structure and balance in the contrast pattern (black).
  • Right example: Least bright (red areas). Most leakage (white). Unbalanced, asymmetrical contrast (black).

Did You Know?  Ideal Scope is rarely seen in stores because it will reveal deficits in most diamonds. Guarantee your diamond has superior performance with standout vetted vendors willing to provide Ideal Scope images, including Whiteflash and

Ideal Scope Chart

In addition to brightness, leakage and contrast, an Ideal Scope also shows a diamond’s optical precision (aka optical symmetry). Some vendors will use an Ideal Scope photo for the ‘arrows’ and a Hearts and Arrows (H&A’s) viewer image for the ‘hearts,’ seen when the diamond is turned upside-down. This is useful, because the Ideal Scope image provides info on the diamond’s light return, where an ‘arrows’ image does not. The main difference is the H&A’s viewer design shows the arrows as white whereas the Ideal Scope shows the same arrows, but as a black eight-pointed star in symmetrical well-cut diamonds (see H&A’s examples).

The Ideal Scope is based on a principle discovered by Kazumi Okuda in the 1970s.


Brightness and Leakage Explained

Depending on the main facet angles, light entering a diamond will either reflect and shoot up to the viewer’s eyes (as brightness) or escape through the bottom (as leakage or windowing). In general terms, brightness is desirable, leakage is to be avoided – with exceptions.

Contrast Explained

Some light from above will always be blocked by the viewer, creating a dark pattern. You can see the contrast effect in diamond photos because the black camera lens blocks light the same way a viewer does. The on and off contrast effect is a dramatic component of scintillation when diamonds move, as darkened facets change rapidly to white or colored flashes, then darken again.

Under optimal lighting: When combined with great brightness, a diamond’s contrast pattern drives the vivid “on-off” suite of white and colored flashes we see as sparkle in brilliant cuts. The amount and distribution is key. Generally speaking, a balanced and symmetrical contrast pattern is desirable.

Contrast in Ideal Scope

Ideal Scope codes light from directly above the diamond black. This simulates the amount of light obstruction caused by the average person’s head at a distance of 25cm (10 inches).

Ideal Scope Logic

See our Diamond Performance Explained page for more illustrations.

Scroll to Top