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Confused by ASET image

lambalan14

Rough_Rock
Joined
Jun 25, 2016
Messages
2
I have received an ASET image which has black arrows.

All the ASET images I have seen on the internet have blue arrows with black/white areas suggesting leakage. Is it possible for an ASET image to have black arrows? I have only seen black arrows on idealscope images.

Thanks.
 

Wink

Ideal_Rock
Trade
Joined
May 3, 2001
Messages
7,516
lambalan14|1466913565|4048432 said:
I have received an ASET image which has black arrows.

All the ASET images I have seen on the internet have blue arrows with black/white areas suggesting leakage. Is it possible for an ASET image to have black arrows? I have only seen black arrows on idealscope images.

Thanks.
The ASET image is based on where the light comes from. The dark blue is coming from 75 to 90 degrees and represents the head shadow that we cause simply by looking at the diamond from a perpendicular to the table view. The black and white that you are talking about is the leakage in an ASET image and will be white or black because that is the background behind the diamond. The best looking images have a black background, while the most revealing images have the white background. The ASET images are taken with the diamond resting on a glass plate with a black cup over the diamond for the black background images and the cup left off for the white background images. The light goes into the top of the diamond through the glass and the colors represent from where the light is coming from and being returned to the eye. Green is light that is entering the diamond from the horizon to 45 degrees and red is that light that is entering the diamond from 45 to 75 degrees.

The inside of the Ideal-Scope that Garry Holloway makes have a black eye piece that is causing the black arrows in the Ideal-Scope. In this instrument the diamond is taking in light from the back of the diamond and where there is leakage it is shown as white. The light that is reflecting from the inside of the eyepiece is shown as red except for the light that is obstructed by the black eyepiece which is shown as black.

They are two completely different tools which give us different information about the diamond, and both are very useful to us cut nuts.

Wink
 

Wink

Ideal_Rock
Trade
Joined
May 3, 2001
Messages
7,516
lambalan14|1466916258|4048442 said:
Thanks Wink. Are you saying it not unusual to find black arrows in an ASET image?
No, I am saying I should not make technical responses just before bed. I believe that this sentence may be where the confusion is coming from. "The light goes into the top of the diamond through the glass and the colors represent from where the light is coming from and being returned to the eye." The light actually enters the ASET from behind the diamond and is reflected into the diamond through the glass and the colors in the diamond tell us where the light entered the diamond from.

Here is a picture of the Idea-Scope and the hand held version of the ASET.

professional-kit-with-dual-light-loupe.jpg

(Photo courtesy of Garry Holloway. Scopes can be purchased from David Atlas.)

You will notice that the ideal scope is red and black in construction and the ASET is green, red and blue in construction. Both of these scopes allow light from behind the diamond to enter the scope and reflect back into the diamond. leakage is where the light enters directly through the diamond to the eye piece and is thus seen by the viewer as white.

In the larger desktop module that I have at the office, the diamond rests face down on a sheet of glass and a black cup can be placed over the diamond if you desire black to be the background and show as leakage or left off if you desire white to be the background and show as leakage. Light still enters the ASET, from behind the diamond and is reflected into the diamond.

When viewing the diamond through the ASET green represents the area from parallel to the table to 45 degrees. Light from these angles is generally less intense than light from above, especially indoors where our main sources of light are above the 45 degree angle if the diamond is held with the table parallel with the floor.

When viewing the diamond through the ASET, red represents the area from 45 to 75 degrees from parallel to the table. This light is generally the most intense light and thus the most desirable, so we want out diamonds to catch a predominance of this light when possible.

When viewing the diamond through the ASET, blue represents the area from 75 to 90 degrees from parallel to the table. This is the area that our head shadow obstructs from receiving direct light when we are observing the diamond from directly overhead.

When the arrows show as black as shown in the images at the link from Flying Pig it is a lighting and photography issue. The tool is designed to show the obstruction area as blue, not black. Black, or white depending on whether or not the black cup is used behind the diamond denote leakage.

Why is all of this important you ask? Because it gives us an indication of how the diamond is going to look to the eye. What is often not spoken of is the FACT that this is a static image from this exact angle. As the diamond moves in relation to the viewer, magic happens. Facets that are obscured and showing blue become lit. Facets that are lit can turn off (be obscured). Some that are red now are catching green, but again, all of this is only from this exact angle of view. To our eyes it is not red, green, blue, black, white or whatever, it is just the MAGIC of sparkle.

Even our heart beat can make the diamond dance as we hold it in front of our eyes. It is this magic, properly called scintillation, that makes diamonds exciting. If a diamond could somehow be cut so that it "perfectly" returned only maximum light to our eyes I suspect it would look like a little mirror and we could see whether or not we shaved in the morning, or had a smudge on our cheek. Which obviously would not be perfect at all. It would be BORING!

Diamond cutting has evolved over the years to allow the cutters to release more of the beauty inside the starting crystal if they choose to do so. Many choose to retain weight at the the cost of losing much of the possible beauty and sparkle so that they can sell the larger diamonds for more money to people who do not understand what they are buying.

Tools, such as the ASET and the Ideal-Scope allow us to see in split seconds whether or not the cutter has done the job to the benefit of the ultimate consumer, or to the benefit of retaining weight.

The danger to the consumer is this. Once he learns to use these tools properly, his diamonds will cost more because they had more cost to the cutter to produce. Oh poor consumer? NOT AT ALL! When the consumer pays more for a diamond that is cut better he will be getting a diamond of greater value. It will have more sparkle, more beauty and make the recipient of his gift happier over the years, thus having much greater VALUE!

My not so secret desire is that eventually consumers will begin to understand and demand this and the cutters who cut the garbage will be forced to improve the quality of their cutting to survive. Average diamond cut quality has improved since the establishment of cut grades by AGS and GIA. GIA did not go far enough, in my opinion, because of so much opposition to the cut grading by the trade, which was happy making that easy money. When the opposition to the steep deep combinations that are being more and more consistently cut to maximize the allowable weight from any given starting crystal become strong enough, then the standards will tighten up.

It will eventually happen and the millions of poorly cut diamonds will loose market value to more correctly reflect their lack of sparkle value. The ASET and the Ideal-Scope are two of the tools that will assist this to happen, because with minimal effort any consumer can see immediately whether or not a diamond is at least well cut. With a little more study they can then go on to select only the best of the best cuts if they choose to do so.

Of course, even with all of the tools and the knowledge to use them, it will always be the eyes that are the final arbiters of do YOU love it with YOUR eyes enough to spend YOUR money on it as THE DIAMOND worthy to represent YOUR love?

To some, good enough is good enough. To others, only the best will be good enough. These tools will help you to know which is which.

Wink
 

poshmommy

Brilliant_Rock
Joined
Jan 28, 2016
Messages
552
Thank you so much, Wink, for the explanation! I am on the hunt for an ideal cut diamond and have been getting a little confused by this myself. Thank yo so much for taking the time to spell everything out for us newbies!
 

Diamond_Hawk

Brilliant_Rock
Trade
Joined
Apr 8, 2014
Messages
1,221
lambalan14,

You have received some very detailed responses about light performance images - what a treasure trove!

Let me answer your initial question succinctly:

If the arrows in the ASET are BLUE that means the image was taken through an ASET viewer in the original set-up. If the arrows in the ASET are BLACK it simply means the photographer has removed the blue portion of the ASET viewer and the camera lens (black) is now being reflected where the blue would normally appear. This is typically done for reasons of focus & depth of field due to diamond size. Most important: As long as the image is BACKLIT (where white is leakage) there is no photographic or lighting issue whatsoever. All is fine. Neither blue or black is superior or inferior. Now in cases where there is no backlighting this can change, which might be what Wink was thinking of. But all is fine here.

For more on ASET interpretation please reference this article from the PriceScope journal:

https://www.pricescope.com/journal/what-aset-reveals-ideal-scope-does-not
 
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