Gemstone Windows and Dark Patches: What to Look for in a Cut Gem

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AI-generated educational illustration. Conceptual only; not a photograph of an actual specimen or location. A coloured gem may have a pale, see-through centre or areas that look almost black. Both affect its appearance, but they do not have the same cause. What is a window? A window is an area where light passes through the gem instead of being returned towards the viewer. You may see the background through it, especially near the centre. Cutting angles and the material's refractive index—how it bends light—help determine whether this happens. There is no single ideal depth for every gemstone. Why dark patches need a closer look Darkness can have several causes. The material may absorb a lot of light. Some facets may reflect dark surroundings or the observer. Extinction is another cause, involving light that is not returned to the viewer after internal reflection. For that reason, calling every black patch “extinction” can be misleading. A simple viewing routine Look at the gem fac...
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Pink Potassium Alum From Afghanistan

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Good afternoon, respectable people, 

The main goal of this post is to share photos of pink potassium alum although Mindat mentioned the Alum group in the list of Afghanistan. But did not find any pictures on the internet when posting this post that represents Afghanistan. 
<br>UNHCR<br>#GGIP<br>#Ruby<br>#Sapphir<br>emeralde#<br>Pakistan
Pink Potassium Alum From Afghanistan 

<br>UNHCR<br>#GGIP<br>#Ruby<br>#Sapphir<br>emeralde#<br>Pakistan
Pink Potassium Alum From Afghanistan 

<br>UNHCR<br>#GGIP<br>#Ruby<br>#Sapphir<br>emeralde#<br>Pakistan
Pink Potassium Alum From Afghanistan 

<br>UNHCR<br>#GGIP<br>#Ruby<br>#Sapphir<br>emeralde#<br>Pakistan
Pink Potassium Alum From Afghanistan 


At the time of posting this post, I am not aware of the exact location of this Pink Potassium alum in Afghanistan. But I hope they will be updated by all of you in the near future.

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