OMC reflects stone interior instead of reflecting light?

[blingergrrrl]

Ok, ok, I am not going to be purchasing anytime soon but I HAVE decided once and for all that I NEED an antique-style OMC (cushion shaped with a ratio of ~1.10)! So, if I have been doing my reading right, the OMC's have a deeper cut that actually reflects the pavilion pattern throughout the stone to draw the looker into the stone to the open cutlet, as opposed to a RB that reflects the light back out the crown to make it more brilliant? Is this right? These are such amazing stones!

For example Valeria101 posted this pic (https://www.pricescope.com/community/threads/modern-cushion-vs-antique-cushion.23890/page-2):

 

[Cehrabehra]

Date: 5/16/2007 4:18:19 PM
Author:blingergrrrl

Ok, ok, I am not going to be purchasing anytime soon but I HAVE decided once and for all that I NEED an antique-style OMC (cushion shaped with a ratio of ~1.10)! So, if I have been doing my reading right, the OMC''s have a deeper cut that actually reflects the pavilion pattern throughout the stone to draw the looker into the stone to the open cutlet, as opposed to a RB that reflects the light back out the crown to make it more brilliant? Is this right? These are such amazing stones!

For example Valeria101 posted this pic (https://www.pricescope.com/community/threads/modern-cushion-vs-antique-cushion.23890/page-2):

What you are seeing in the stone where the culet is reflected over and again is called the kozibe effect. Some might consider it a detriment (particularly if you''re looking for a H&A round brilliant) but many OMC lovers find this a gorgeous effect. Kozibe http://www.octonus.com/oct/products/3dcalc/standard/param16.phtml in the stone you''ve shown above is such that the stone doesn''t needed to be tilted even a little bit for the culet to be seen multiply in the crown. All diamonds will show this effect at an angle, but stones with open culets do take the cake on it I think - the open culet gives a more grounded point for the effect to reflect on giving a house of mirrors sort of look to it.

Light doesn''t exactly disappear. It is absorbed and reflected. When it hits your skin, most of the light is absorbed except that which is the hue of your skin and that is reflected back. When the diamond hits the table of your stone, some bounces off and some goes in... when it hits the pavillion of your stone some bounces back out and some goes through. The trick to diamond cutting is to harness the light coming in from overhead, bouncing it around as little as possible, and sending it back out through the top. At least that''s a very sarasimplied view of rounds. Many don''t want light to leave anywhere but the top of the diamond so it doesn''t matter if the diamond is enclosed in a bezel or whatever, the goal is light from the top in, light going out through the top. With these old cut stones that wasn''t really the goal and some of us think there is more to a beautiful diamond than harnessing light from overhead and putting it back out the way it came. So then you get these stones like the one above who more than likely DO do a pretty good job of putting the light out through the top, but might also throw light in other directions and *receive* light from other directions. I''ve seen IRBs and they definitely beat my stone in top up bright whiteness.... but my stone glows from every angle with rainbows coming out all over and I prefer that. And the *dark* culet dots you see all over the stone in the above pic, that''s just reflection of the camera lens. The lens looks straight through the culet and sees the light behind it, but what the back of the pavillion/culet sees is the camera and it reflects that out which will give contrast and scint. And keep in mind those wouldn''t always be dark, they''d be reflecting light from all over as well as refracting it. I wouldn''t go so far as to say that an omc''s job is to not reflect the light and instead to reflect the pavillion, but I would say that reflecting the white light out is not its best feature. IRBs give a very white look with colored splinters of INTENSE fire, but it is designed to give this light show in a particular viewing angle. OMCs, at least mine, are still cut to return MOST of their light up, but I''ve never been disappointed to have a 360* viewing range

 

[blingergrrrl]

WOW that is such an amazing sarasimplified answer!!

That totally makes sense! So would you say then that because OMCs are not as brilliant as IRBs that the color of the stone shows more? I would of been comfortable going to a I-(high)J in a IRB due to the face that they face up whiter, should I try to look a little "cooler" in a OMC to still get a relative appearance?

 

[Garry H (Cut Nut)]

Approximate order of effect of parameters in making it possible to see the culet (Kozibie)

Steeper Crown angle
smaller table
bigger culet
(out of round - you can see 4 culets)
deeper pavilion
thicker girdle

Of course diamonds with combinations of these things - like many old mine cuts - have more chance to show the culet.

 

[surfgirl]

Well, I dont know nuth''in ''bout no Kozibie effect but in my European/Transitional cut stone, I can see reflected culets in certain lighting and I have crazy scintillation and insane color bursts from all sides of my stone, including my culet...but I do not have a steep crown (the proportions are closer to a RB than an OMC), nor do I have a thick girdle (in fact the girdle is very thin).

 

[Cehrabehra]

Date: 5/17/2007 1:07:11 AM
Author: blingergrrrl
WOW that is such an amazing sarasimplified answer!!

That totally makes sense! So would you say then that because OMCs are not as brilliant as IRBs that the color of the stone shows more? I would of been comfortable going to a I-(high)J in a IRB due to the face that they face up whiter, should I try to look a little ''cooler'' in a OMC to still get a relative appearance?

it isn''t quite so much that emerald cut and omc cuts show MORE color than rounds, its that rounds show LESS color - if that makes sense? they are so good at returning the white light that it gives the impression of a whiter stone. I can''t post it, but I have a pic of my stone on my finger next to a round brilliant cut and I took a pic with a flash and the round is light a white hubcap and my stone doesn''t have an overall brilliance reall and looks kinda yellow in the pic, but the whole thing is covered in rainbow sparkles - like dozens of them.... for me it was a choice I wanted rainbows in a *big* way but wasn''t concerned with the white look. Its a balance.... there are extremes both ways....