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Black Arrows.


JB12345
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That difference is a product of crown angle and pavillion angle combinations. Crown angle ranging between 34° - 36° with combination of pavillion angle between 40.6° - 41° will produce better contrast patterns and consequently those black arrows. Those are black because the environment right in front of it is black (because of camera and light being blocked from the front). These could bre any color depending on the environment. The other stone may have different crown and pavillion angle combinations and reflecting other things in the environment instead of the absolute front (camera and darkness because of light blockage). 

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9 minutes ago, Furqan Shafi said:

That difference is a product of crown angle and pavillion angle combinations. Crown angle ranging between 34° - 36° with combination of pavillion angle between 40.6° - 41° will produce better contrast patterns and consequently those black arrows. Those are black because the environment right in front of it is black (because of camera and light being blocked from the front). These could bre any color depending on the environment. The other stone may have different crown and pavillion angle combinations and reflecting other things in the environment instead of the absolute front (camera and darkness because of light blockage). 

So something to look out for would be crown and pavillion angles that fall into 34° - 36° & 40.6° - 41°. Anything outside that range could be less desirable?

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These are not Hearts and Arrow pictures.  These are face up pictures of stones taken in similar but not necessarily the same light conditions/camera angles, etc...

To evaluate H&A you need to use consistently taken H&A pictures in a controlled reflector environment.  you cannot use these pictures to evaluate the H&A pattern.  As Furquan explains, the H&A pattern is a result of angle combination as well as facet proportion and symmetry.  In desktop photography such as the images you have posted, the photographic set up introduces a number of other variables that have nothing to do with the stone but do affect the look of the image.

 

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1 minute ago, LaurentGeorge said:

These are not Hearts and Arrow pictures.  These are face up pictures of stones taken in similar but not necessarily the same light conditions/camera angles, etc...

To evaluate H&A you need to use consistently taken H&A pictures in a controlled reflector environment.  you cannot use these pictures to evaluate the H&A pattern.  As Furquan explains, the H&A pattern is a result of angle combination as well as facet proportion and symmetry.  In desktop photography such as the images you have posted, the photographic set up introduces a number of other variables that have nothing to do with the stone but do affect the look of the image.

 

So desktop images are good for looking for inclusions, symmetry and colour but not much else.

For checking the cut the use of the HCA tool. (<2 is good to start selecting.) and Ideal scope - aset scope and h&a.

is this correct?

 

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1 minute ago, JB12345 said:

 

So desktop images are good for looking for inclusions, symmetry and colour but not much else.

For checking the cut the use of the HCA tool. (<2 is good to start selecting.) and Ideal scope - aset scope and h&a.

is this correct?

 

According to some - on a particular internet forum. 

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The HCA is only useful if you happen to have the same taste as the person who created it and monetized it.  Many of us have differing views and appreciations so we do not put much/any stock in that particular tool, but there is another forum, chock full of opinions but light on actual hands-on experience where they push this tool. 

IS, ASET and H&A can be useful is weeding out non-performers, but seeing the stone is always the best way to judge its cut.

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