The Helium Scanner - Model Maker Extrordinaire
""With the rollout of the new AGS cut grading system, it is important that the diamond industry be able to create accurate three-dimensional models..." Pete Yantzer, Executive Director, AGS Laboratories
"The science supporting the new cut grade system reflects AGS’ transition from a proportion-based to a performance-based cut grade system, where all facets of a diamond are measured in three dimensions rather than two dimensions. The Lab will use state-of-the-art ray tracing software to trace light traveling through a diamond. The software demonstrates the quantity and quality of the light being returned to the viewer. AGS Laboratories will now consider brightness, dispersion, leakage, contrast, and weight ratio, in addition to proportion, symmetry, and polish, when assigning a final cut grade." Pete Yantzer, Executite Director, AGS Laboratories.
Realizing the importance that 3d model making will be in the new cut grading system (particularly AGS'), it is with great pleasure I introduce you to what is considered the worlds most accurate diamond scanner, Helium, made by Octonus Inc. a Russian based outfit based at Moscow State University (MSU). In the USA we are only one of 3 laboratories to feature the Helium Scanner besides AGS and GIA making us the only lab/store in the country to offer the services provided by the Helium Scanner.
Let's examine some of these features.
One of the true tests to determine the accuracy of a scanner is its ability to resolve each facet, from point to point and be able to compare its model with the actual diamond it had scanned. The details are so fine you can see, from the model exactly where facet points meet or don't meet making it one of the best tools for determing symmetry and proportions, based entirely on the model alone. Here is an example.
In the red circle is where 2 lower half facets do not meet at the junction point properly (minor symmetry feature). In the yellow circle is a natural or if it was an extra facet would be a major symmetry feature.
Minor Symmetry feature:
Facet junction pointing not proper.
Photo of diamond
Photo with model
Major symmetry feature:
Extra facet or natural
Photo of diamond
Photo with model
Here's a comparison of the same stone scanned with both Sarin and Helium.
This is one primary reason we utilize the Helium Scanner. The other is the Reports this thing can generate!
The Helium Reports we feature on the web consist of their "Illustrated Report" for ease of use for the consumer or gemologist consulting this data which we upload in Adobe .pdf format. You'll need the free Adobe reader software which come standard on many computers today. If you don't have it you can get it here.
You can click on the graphic below to pull up an "Illustrated Report" we generated on a diamond from our inventory.
We'll examine this in some detail by sections.
This first section in the upper right shows
a. The calculated weight of the diamond as based on the volume of the dimensions. We find this to be extremely accurate in just about every instance. This diamond weights 1.63ct.
b. Also given are the average measurements for each facet set excluding upper girdles.
c. It also includes lower girdle facet length and depth. GIA uses the "length" measurement so if one were to input the numbers into their FacetWare program that is the figure they would use in that field.
d. The profile shown in this graphic is of the actual diamond scanned.
In the bottom portion of the 1st column we see precisely where on the diamond that the minimum and maximum diameter measurements are taken. The face down and face up views shown are based on the actual scan as well and shows how the facets on the other side of the diamond reflect within the stone. If there were any 3 dimensional deviations we'd see it here. At the bottom of this section we input the AGS polish and symmetry grade. NOTE: The cut grade assigned here is the old AGS Cut grade prior to June 2005, not the current one.
As we move to the top of the 2nd column we get all the details regarding min and max measurements on each facet set. The Dev column refers to how much these facets deviate from min to max looking at the "variances" we discussed in our chapter on Sarin. The guys over at MSU are real anal and check even the minor facet variances. (note: minor facets consist of lower girdle, star and upper girdle facets, 40 in total).
It is virtually impossible for a diamond to receive an EX in every facet set since such minutae is examined in the Helium Report. Each facet set is listed in the first column.
The 3rd column shows the precise measures of every facet within each facet set. These details are included in printed for with our appraisals as well.
In the lower middle section (blown up here) we get some more excellent data.
The first table shows us how much each of the facet set deviates from its ideal azimuth angles.
In this table we primarily look at the deviation on the pavilion angles, lower girdle facets and lastly crown angles. The more that facets deviate from their ideal azimuth position the more light is redirected out of the diamond in an assymetrical manner. For a more detailed discussion on how the observance of light return is affected (in a critical exam) by altering azimuth angles I refer you here and scroll down to the paragraph entitled Azimuth Angles.
The 2nd part of this illustration shows at a glance every facet angle on each individual facet and the graphic is based on the actual scan of the diamond. Comparing these grahics shows the user instantly if the stone is precision cut or sloppy. Check out the comparison beneath.
The last section in the bottom right are graphs showing data pertaining to the
a. girdle cutting
b. diameter deviation
c. radius deviation
The diameter and radius deviation relate to how much the diamond is out of round or not. To get an idea we'll make a further comparison below.
The "Girdle Thickness" graph can show the user graphically if the girdle cutting was
a. wavy or disproportionate
b. too thin or too thick
c. painted or dug out (we show how to see those results through this graph here)
The "Girdle type" at the very bottom will generally fall into one of 3 categories.
1. Classical (as in this example) would describe the classic ideal girdle.
2. If you've read our tutorial on "Painting and Digging", the Helium Report does not incorporate traditional trade terminology into this field just yet so it could be a little misleading. A painted girdle is described in this field as being "dug out (gouging)" while a dug out girdle is described as "thinning (gouging).