Nail Head vs. Fish Eye????

[curious]

Please clafify a NAIL HEAD EFFECT and a FISH EYE EFFECT.

I have thoroughly read the tutorial and am still confused.

If possible, can you show some pictures of diamonds with these effects.

Muchas Gracias!!!

 

[pricescope]

Hi Curious,

Fisheye: reflection of the girdle is visible under the table in the face-up position. It happens when diamond has shallow pavilion and large table:

Nailhead: table of the diamond appears very dark. This happens when pavilion is too deep.

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[Garry H (Cut Nut)]

My diamond cut nerd work has been done so well by the computer nerd

 

[curious]

Thanks for the great pics...they helped a lot.

Why do round stones seem to have a black dot in the middle where all the facets come together? Is this a natural effect?

 

[curious]

How deep of a pavilion will cause the nail-head effect????

 

[pricescope]

You can find the chart here:


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[Garry H (Cut Nut)]

It also depends on the size of your head (he he he).
Actually it does, because the rays perpendicular to the table in a diamond with a 45 degree pavilion angle go right back to where they came.
A nailhead shows you a picture of your head as seen from the inside of the diamond.
A big dark head person with a big black hair style gets a worse nailhead than a petite blonde.
Life is funny don't you think?
We talk about the diamonds, but the observer and the environment is also a critical factor.

 

[curious]

This chart is like reading Chinese.....?????????

 

[Garry H (Cut Nut)]

Sorry Curious you are wrong, it is Russian

The info there is very technical from leonid and my good friends at Moscow State uni.
You will not be asked to sit any exams.