True black carbon in diamond from an image

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    Carbon Diamond Image
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Discussion Overview

The discussion revolves around the challenge of identifying true black carbon inclusions in diamonds from images, particularly distinguishing these from black spots caused by total internal reflection (TIR). The scope includes theoretical considerations of light behavior in diamonds and practical imaging techniques.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant expresses difficulty in identifying true black carbons in diamond images and seeks methods to filter out artifacts from total internal reflection.
  • Another participant challenges the assumption that TIR can create black spots in images, arguing that light from any point in the diamond should be accessible and illuminated.
  • A different participant acknowledges that black carbons are natural inclusions in diamonds and suggests that TIR may cause confusion in distinguishing these inclusions from other features.
  • There is a suggestion that using a liquid with a high refractive index could help, although the original poster is not considering this option.
  • One participant proposes using wavelengths where diamond has a normal refractive index, such as VUV or X-rays, but acknowledges that these methods are impractical for everyday use.
  • A later post humorously requests "alien technology" to solve the problem, indicating a sense of frustration with the current limitations.
  • Another participant seeks assistance from those familiar with optical engineering, indicating a desire for expert input on the issue.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the effects of total internal reflection on the appearance of black spots in diamond images. There are competing views on whether TIR can obscure true inclusions and how best to identify them.

Contextual Notes

Participants express limitations in their approaches, including the impracticality of certain imaging techniques and the constraints of not using a solvent with a similar refractive index to diamond.

Who May Find This Useful

This discussion may be of interest to gemologists, optical engineers, and researchers in materials science who are exploring the properties of diamonds and methods for analyzing inclusions.

sty2004
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I have difficulties in finding the true black carbons in a diamond from an image.

Since diamond has a high refractive index of 2.42, it has a critical angle of 24 degrees such that total internal reflection can easily occur (total internal reflection causes fire in diamond) . Now I have taken an image, my main focus is on black carbon. I want to solely find out the true black carbons without those due to total internal reflection. Is there a way to distinguish the difference or filter out the TIR except for looking at the similarities in shape of the black carbons. This looks like an everyday problem but no one really cares its application, please help~~~~

Also I will not consider putting the diamond in an solvent of similar refractive index as diamond. And I know that an image cannot tell all black carbon inside the diamond.
 
Last edited:
Physics news on Phys.org
Please give me some ideas~~
 
You seem to believe that total internal reflection will result in the appearance of black spots in the image that results from looking into a facetted diamond.

As I understand it, working from first principles on the assumption of a convex diamond, total internal reflection will never result in any external viewing angles becoming inaccessible to light originating from a given point in the interior of the diamond.

It follows that there are no points in the interior of the diamond that are not illuminated by light originating at an arbitrarily chosen point source.

So I just don't get how you think that black spots can result from total internal reflection.
 
The pointed-to web page has a picture. It contains no argument for the claim that total internal reflection can cause black spots in the picture of a diamond.

Perhaps the claim is that internal fracture planes can cause light to fail to pass at certain angles and that this is difficult to distinguish from an inclusion that actually absorbs light.

That would certainly fail to meet the "convex" premise in the argument that I gave.
 
The easiest way would be to immerge the diamond in a liquid with a high refractive index. But you don't want to do that, for whatever reason.

The second possibility is to take an image using a wavelength where diamond has a "normal" refractive index close to 1. VUV or X-rays seem to fit the bill, but these are measurements you cannot do in your kitchen sink.

Walker, W. C. and J. Osantowski, Phys. Rev. 134, 1A (1964) A153-A157.
 
@jbriggs444
Thanks
@M Quack
I am afriad that VUV or X-rays have been considered by my team. Anyway, thanks for your reply.
 
Can anyone provide me some sort of alien technology?
 
Anyone familiar with optical engineering can help me?
 

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