Fish-eye effect with a Radiant?

[kace]

I''ve read about fish-eye effect in reference to a round diamond. Is there a fish-eye effect with radiants or other fancy cuts?

 

[diamondsbylauren]

Hi Kace-
Absolutely- it is possible to have a "Fish Eye" in an "off make" radiant cut diamond

 

[Kaleigh]

So you can have a fish eye occur in most any shape???

 

[tat2db]

Absolutely. I was shown a radiant recently that had a fisheye. It was more visible away from direct light. I chose to pass on the stone for this reason!

 

[Garry H (Cut Nut)]

I think it may be impossible to find a radiant without a fisheye effect .
But most of what appears to be fisheye in radiants is leakage out the pavilion.

 

[kace]

Thanks, everybody, for clarifying this. Is there a picture of a fish-eye radiant you can point me to? I''ve been looking at radiants, and I don''t think that I''m recognizing a fish-eye in a radiant.

 

[Garry H (Cut Nut)]

Whiteflash and Goodoldgold each have ideal-scope photo''s and relaistic photos
you will see it all the time.
You can also look at Laurens photo''s - sometimes his images will appear to sparkle from the fish eye / leaakage zones

 

[diamondsbylauren]

In basic terms a fisheye is what happens when a round diamond is too shallow.
When I was trained on the most basic aspects of the cut of a diamond we learned that if the diamond was too deep, the center looked dark.
If the stone was too shallow, you'd see a white ring inside the table that looked like..... a fish's eye.

The training began on single cut diamonds- these have only 8 facets above the girdle, and 8 below.
It is so easy to see if a single cut diamond is cut badly after you are shown what to look for.
Which, by the way, is also true of modern Round Brilliant Cut Diamonds too.

Every round brilliant starts out as a single cut.

Anyway- back to the topic at hand...A radiant cut uses angles which are NOT avaiable in a round brilliant to maximize sparkle. Remember, we have corners on Radiant Cut diamonds.
Well cut Radiant cut diamonds have polished or faceted girdles- the girdle is important in the look of the stone.
Garry's comment about not being able to find a Radiant without a fisheye ( yes, of course I disagree ) may be based in the way a radiant cut uses the girdle in it's sparkle. We like to use the term "bucket of crushed ice" - that's a very good way to describe the way the light bounces around in a well cut Radiant cut diamond.


If you want hearts and arrows- or similar type of pattern in your Radiant -like diamond, it must be square, with large corners- Iam not an expert in the square H&A diamonds- does anyone know if Rectangular H&A diamonds?

In some of my photos, a ring is visible in the center of the diamond. In others a diamond shape in the middle.
One aspect of photography is that it freezes a moment in time - which is not really possible when veiwing a diamond in real life. There's always movement- even subtle movement and changes in light if you hold your hand perfectly still as you can.


When people talk about "light leakage" have one thing in mond- they are not wrong- but neither are people who feel that some "windows" in a fancy shape diamond are an essential part of the personality people love so much.

Most Fancy Shapes are simply not "regular"

Kace- If you saw a badly cut Radiant with a detrimental fish eye effect- they do exist- you wil notice it easily

 

[valeria101]

Taking ''fish eye'' to be a visible reflection of the girdle onto pavilion facets within the vertical projection of the table...

thick girdles, shallow pavilions and large tables all help to get the fish out of a diamond.

For example, if there is a laser inscription of an ''extremely thick'' girdle, the right tilt and pavilion angle, this is what you get:

(see the repeated reflections of the girdle inscription on pavilion facets between 12 and 2 o''clock or so)

I don''t know if this one does show ''fish eye'' all that much in person because this picture is tilted (easy to spot that tilt - the culet shows offcenter and everything else aligns).

The pictures taken to show optical symmetry are the best at showing fish eye - they are very detailed and perfectly centered too. However, it is hard to tell when the picture exagerates the reality and how badly.

Another example for this one below: Regents have wide girdles on the sides (a characteristic of the cut), and those patches reflect nicely as ''fish eye'', almost every Ideal Scope picture of a Regent shows this, only some have it more than others. Whether this is a detraction for the respective cut depends on what exactly shows in person, of course.

The ''poster kid'' for Regents on GOG shows This one has some more - enough to show
just some neglijable trace of fish (the white in the clarity pictures too.
third circle around the table from 3 to
6 o''clock in the picture)

Hope I am right with these Garry.

 

[Garry H (Cut Nut)]

Great examples Ana.

I studies the regent very carefully when they were first released. the fisheye from the very wide girdles at the flat sides actually act as crown facets when the stone is set with then open (which is normal). The light entering the girdle from a low area often leaves via the table as fire.

This image shows the typical problen with the Radiant - the light is often directed below the horizon to dark spots like the floor

 

[Ann]

I posted a picture a while back of a radiant with what I thought was a poor cut - a circle when you looked deep into the stone.
Do a search - I know it is there - somewhere. I''ll see if i can find it.

 

[Ann]

https://www.pricescope.com/community/threads/seeing-circle-effect-in-a-radiant.29069/=

I think this is it.