Ideal Scope Explained

Ideal Scope – Basics

The Ideal Scope is based on a principle discovered by Kazumi Okuda in the 1970s. A lens with a hot pink reflector lets you see how much light comes from the diamond to your eyes.

Garry Holloway uses one of his Ideal-Scopes
Garry Holloway uses one of his Ideal-Scopes

An Ideal Scope is a portable diamond brilliance and leakage gauge. The most brilliant diamonds have pink/red (brightness) with a symmetrical black star (contrast) and minimal white or pale areas (leakage).

ideal scope explained

White areas in a diamond show light transmitted from under or behind the diamond called leakage – the enemy! The blackness of the lens mimics an observer’s head blocking out the light. Ideal cut round diamonds have small ‘V’ shaped white leakage features at the girdle.

ideal scope examples

An Ideal Scope also shows a diamond’s optical symmetry (aka optical precision) and some vendors will use an Ideal Scope photo for the ‘arrows’ and a Hearts and Arrows (H&A’s) viewer image for the ‘hearts’ or rear of the diamond. This is a great idea because the Ideal Scope image provides more info on the diamond’s cut than an arrows image. The main difference is the H&A’s viewer shows the arrows as white whereas the Ideal Scope shows a black eight-pointed star in symmetrical well-cut diamonds. Both scopes are a by-product of Mr. Okuda’s discovery.

Ideal-Scope reference chart
Ideal-Scope reference chart


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Garry Holloway BSc, FGAA, DipDT, NCJV.

Learn about ASET-scope here.

See our page on Diamond Performance Explained

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