The American Gem Society An Introduction to ASET Theory & Technology

The American Gem Society An Introduction to ASET Theory & Technology

The angular spectrum refers to the set of ray angle directions that can make a gem s s facet bright. José Sasián, Ph.D. Optical Physicist University of Arizona

For decades, jewelers have discussed diamonds in technical terms s using averages of angles and percentages of only 17 facets. Today, light performance evaluation addresses all 58 facets in three dimensions. ns. 1983 Today

The Angular Spectrum Angular Spectrum Evaluation Technology allows us to visually perceive how efficiently, or inefficiently, a diamond is handling light. This is done by producing a color-coded coded image of the diamond using the colors RED, GREEN, BLUE, and BLACK or WHITE that identify the angles or angular spectrum from which the diamond is gathering light. These colors demonstrate what is referred to as LIGHT PERFORMANCE.

What the colors in an ASET image demonstrate: RED represents the brightest light that makes the diamond brilliant.. It strikes the diamond from 45 up to perpendicular to the table. GREEN represents light that is not as bright. It has been reflected off o of objects or from indirect angles. This is light that strikes the diamond from 45 out to the horizon. Ideally, we want to see much more red than green with only one exception: e The table reflection area in the very center. It could possibly appear red, green, or occasionally a combination of both. That s s acceptable.

BLUE represents Contrast. It is the pattern of light and dark areas that our eye finds pleasing. It is caused by light that could have entered the diamond but which is blocked by the viewer s s head. It should be distributed in a balanced & symmetrical pattern. BLACK or WHITE (depending upon the lighting environment used) represent Leakage, which is an area from which light is literally lost. There should d be very little of this.

What an ASET Image Can Tell You: Light Performance: Optical Efficiency Optical Symmetry Physical Symmetry The Cutter s s Expertise Each image is a Unique Thumbprint

There are two different types of ASET images: Actual images seen through an ASET device and computer-generated images. The computer-generated images are simplified, idealized and two-dimensional. The actual ASET images show much more detail in three dimensions. Actual image ASET Computer-generated ASET

In this computer generated ASET image of an extremely well cut round r brilliant diamond you see the colors broken out into the individual components. The distribution and balance of the colors are vitally important!

Computer-generated examples RBC Princess High Light Performance Medium Light Performance Low Light Performance

The American Gem Society uses a 0-100 nomenclature for the Cut, Color, and Clarity grades of a diamond. 0, or AGS Ideal, is the best or highest grade possible. 10 is the lowest possible grade. It is simple, accurate, and consistent. When speaking of Light Performance,, which is what an ASET image demonstrates, the following descriptions are used: High Performance = 0-20 2 (The term AGS Ideal only applies to 0) Medium Performance = 3-73 Low Performance = 8-108

AGS Ideal Light Performance: L to R: All AGS 0 High Light Performance: L to R: AGS 1, 1, 2,1 Medium Light Performance: L to R: AGS 3, 4, 4, 5 Low Light Performance: L to R: AGS 8, 8, 9, 10

ASET images are particularly helpful to diamond buyers. Certain types of patterns are indicative of common cutting traits. For example: e: Round brilliant diamonds, with AGS Ideal Light Performance, commonly display images similar to this one. Notice the balanced distribution of colors and the eight-rayed blue star terminating in arrowheads under the bezel facets. This type of image is commonly seen with round diamonds that are cut to a shallow standard relative to their table size. Notice the arrowheads now look more like paddles on a bright red background. An image of this nature is commonly seen with round diamonds that are cut too steep relative to their table size. Notice how the arrowheads now look more like red paddles on a predominantly green background.

Not only does ASET technology allow us to immediately see how well a round brilliant cut diamond is using light, it works with ALL shapes of diamonds! Each shape has its own set of Light Performance standards, unique e expectations and capabilities. For example, you would expect to see more green in i most all fancy shaped cutting patterns as compared with a round brilliant.

ASET technology works with both loose and mounted diamonds! Illustrated above are two diamonds before and after mounting into o a six pronged crown and a full bezel.

The Angular Spectrum Evaluation Tools: Together, they form a team that has many different applications. The ASET Camera For more detailed instructions on how to use the ASET tools, please refer to the individual tutorials. The Presentation ASET The Handheld ASET

The Presentation ASET was designed specifically to be used at the sales counter with customers. It is easy to use with either loose or mounted diamonds. It is currently available exclusively to members of the American Gem Society.

Actual images as seen in the Presentation ASET.

The Handheld ASET is used much like a jeweler s loupe. When using a Handheld ASET, Leakage turns white. The emerald cut image below, on the left, was taken with a Handheld ASET; the princess cut image on the right with a Presentation ASET. Notice the differences in how leakage appears in the two tools.

The ASET Camera allows you to capture images on your computer and d to then use them in a variety of ways. Buyers, appraisers and sales associates ates alike find that the ASET Camera is an invaluable tool.

Actual ASET Camera Images

The appraiser can save the ASET image onto an appraisal form. The custom manufacturing jeweler can place an ASET image onto a work order form. In both cases professionalism is enhanced, customer concerns over r the identity of the diamond are minimized and potential problems are avoided.

Showing a client their diamond s ASET image, before and after mounting, builds confidence, eliminates doubt, and enhances value.

An ASET image aids a diamond buyer greatly! It allows the buyer to perceive cutting variations that are difficult to spot with magnification alone. 12:00 9:00 3:00 6:00 This is an example of how square modified brilliant diamonds can be quickly analyzed. Mentally divide square or rectangular diamonds into triangular quadrants: Commonly, they don t t match.

Examples of princess cut diamonds with varying degrees of Light Performance. Light Performance: 0 or Ideal Light Performance: 2 Light Performance: 4

Matching diamonds with the ASET Diamond buyers love the ASET tool to sort and match diamonds based upon how they Perform rather than by their dimensions alone. This speeds up the matching process greatly. Saving time = SAVING MONEY! It is an invaluable tool when it comes to custom manufacturing, repair work, and matching diamonds for new inventory such as earrings where matching is important from both an esthetic standpoint as well as a value standpoint. One mistake when matching melee can ruin a complex and expensive custom repair job. Such a mistake can irreparably tarnish a jeweler s reputation & image in the mind of the client and result in a very costly do-over.

The image you see below could represent a parcel of diamonds each h of which has the same carat weight. All of them could have matching color grades,, clarity grades and dimensions. They all sell for the same price per carat but they have RADICALLY different cutting standards and Light Performance characteristics. s. With the help of ASET technology, a buyer can easily choose which h diamonds are a good value and which ones are not and thus demonstrating to a client the professionalism of the jeweler. It is a HUGE value enhancer.

Matching diamonds with the ASET In each of the three rows of 5 diamonds illustrated above, one diamond d is significantly different than the others. Can you pick out the mismatched diamonds?

Applications of ASET Technology Diamond Selection: Buying new inventory. Evaluating current inventory. Matching diamonds with PERFORMANCE rather than dimensions alone. Selling: Demonstrate Light Performance in a fun and easy manner! Present diamonds in a completely new way. Focus on romance and beauty. Eliminate the guesswork relative to Cut. Appraising: Document value assessments more accurately. Generate more detailed reports. Ease client worries and help them to identify their own diamonds.

If you have questions or for additional information please contact: Patrick B. Stout Certified Gemologist Appraiser Education Services Manager (702) 255-6500 ext. 1020 pstout@ags.org