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Do your diamonds leak light?

This is a simple test you must perform on every diamond you are considering.

Even a high-graded GIA diamond can leak light and look dull.

Since 1999, Holloway Diamonds have used an Ideal-Scope to measure the light leakage of diamonds and reject those that have high leakage and in return are dull and don’t sparkle.


Garry Holloway designed the Ideal-Scope as a portable and affordable method to grade the cut quality of diamonds. In 2001 he decided to mass produce and make them freely available. They are now use world wide by industry cutters.

For our customers, the instrument is simply a lens with a hot pink reflector in front of the diamond and a central viewing hole. With it, you can see just how much of the red/pink light refracts back from the diamond.

Anyone can intuitively gauge a diamond’s brilliance; white areas in a diamond show light transmitted from behind the diamond which we call leakage – the enemy!

The blackness of the lens mimics the light obscuration of an observer’s head and body; too much is bad and too little indicates the diamond will have poor scintillation. The lens creates the star pattern which indicates the symmetrical quality of the diamond. Symmetrical round diamonds are sometimes sold as Hearts and Arrows (H&A) but a H&A’s viewer does not show the leakage which is often present in many H&A’s diamonds.

The most brilliant diamonds look bright pink/red with a black star and minimal white or pale areas except for the small ‘V’ shaped white leakage areas near the edge of the stone.

When buying our diamonds we use this process every time and reject over 95% of the diamonds we are presented with:

Firstly each diamond parcel is viewed with an Ideal-Scope; 4 or 5 stones are assessed in a minute. This usually results in a rejection of 60% to 90% of all supposedly well-cut diamonds.

Then each stone is examined for Colour (we reject everything below an H master stone) and Clarity (rejecting eye visible and diamonds with reduced transparency). On a buying trip, we will examine more than 1,000 diamonds a day.

The idea behind the Ideal-scope was used to develop the ASET scope which Garry Holloway made under license for the American Gem Society. AGS use the ASET as the basis for their Princess and other ‘fancy shaped’ diamond cut grading system. OctoNus developed a software visualization program with Moscow State University that incorporated Ideal-scope and ASET views into their DiamCalc software. The diamond cutters we work with use this software in the planning of the cutting of larger Holloway diamonds.


Test it at home for yourself with your own Ideal-Scope card. Simply click the link below, leave your details and I’ll mail one to you.

Click Here for Your – FREE IDEAL-SCOPE CARD 

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Diamond Tutorial Home

White areas in a diamond show light transmitted from behind the diamond, often called leakage

The ideal-Scope is a magnifying tube fitted with a red reflector.

The ideal scope and the Angular Spectrum Evaluation Tool (ASET)

Seeing leakage makes it easier to discern good from poor stones.
Using an Ideal-Scope and an ASET scope


An ideal cut diamond is a round, brilliant, or princess cut diamond.
Holloway Ideal Cut minimal white areas and a good symmetrical star


An ideal cut diamond is a round, brilliant, or princess cut diamond.
Poor Cut lots of white leakage and random symmetry