Fisheye and Nailhead

[pyramid]

An aquaintance has a ring which I can see the girdle through the table, I can also see that the table of the stone is very dark when someones head is blocking the light. Is this a fisheye and a nailhead. Is it possible to have both these features on ONE diamond? The bottom pavillion facets also seem to show beside the star facets in some lights. It does not seem to be a well cut stone but I ofcourse would never say anything to that person. The table also seems to be big on the diamond.

 

[Garry H (Cut Nut)]

Well done Pyramid

Fisheye's are too shallow and also direct a lot of the light toward the oservers head, just as a very deep diamond does. Sergey calls them Shallow nail heads. you can read a lot about this at www.cutstudy.com - there is an article by Bruce Harding (Beryl) there with a simple explanation and ray paths etc that he wrote in the 1970's.

 

[Serg]

----------------
On 3/31/2003 6:59

0 AM Cut Nut wrote:

Well done Pyramid

Fisheye's are too shallow and also direct a lot of the light toward the oservers head, just as a very deep diamond does. Sergey calls them Shallow nail heads. you can read a lot about this at www.cutstudy.com - there is an article by Bruce Harding (Beryl) there with a simple explanation and ray paths etc that he wrote in the 1970's.
----------------

Garry,

Fisheye's do not depends from crown angle.
Shallow nail depends from relationship between Pavilion and crown angles.
I never said that Fisheye's diamond must have Shallow nail.
It can only.

 

[Garry H (Cut Nut)]

)

Its a good thing I know what you mean Sergey

 

[ociopia]

I don't know at all what the "fisheye" or "nailhead" is but now I'm wondering - I have seen a number of 2 carat+ rb's that look like they have "big, open holes" for a table with very little light action. Definitely "spready." Is this what you all mean or is this something else entirely?

Sherry

 

[Richard Sherwood]

Fisheye- simulated IdealScope (shallow crown - shallow pavilion)

 

[Richard Sherwood]

Fisheye- simulated PhotoReal (shallow crown - shallow pavilion)

 

[Richard Sherwood]

Nailhead- simulated IdealScope (steep crown - deep pavilion)

 

[Richard Sherwood]

Nailhead- simulated PhotoReal (steep crown - deep pavilion)

 

[Richard Sherwood]

"Shallow (fisheye) nailhead"? (steep crown - shallow pavilion)

 

[Richard Sherwood]

"Shallow (fisheye) nailhead"? (steep crown - shallow pavilion)

 

[Richard Sherwood]

try that one again...."Shallow (fisheye) nailhead"? (steep crown - shallow pavilion)