shape
carat
color
clarity

Table shadowing/obstruction in OECs (help, old cut experts!)

camomof4

Rough_Rock
Joined
Sep 5, 2015
Messages
64
HI all,

I've recently looked at a couple of lovely larger-size OEC diamonds, both loose and in settings in antique jewelry stores. In some stones I've noticed the following phenomenon:

When wearing the stone on my hand, and looking down at it from a slight angle (so that the stone face is not facing me directly but rather facing up to the wall or ceiling) the stone is bright bright bright, white, and brilliant. However, when I tilt the stone ever so slightly to look at it head on, I can see the reflection of my head in the table facets which turns the table a little shadowy. It's not that the table goes black, like a nail head - there is still some light return. But I can literally see the reflection of my skin and hair (or my phone case if I'm taking a picture) in the table facets like a mirror, and it impacts the brightness of the stone's face. I notice this starting at a distance of about 18 inches from my face or so.

Is this the phenomenon known as obstruction? How much of this is just to be expected in old cuts (or in diamonds in general)? I'm not sure I've ever really paid attention to this before but now that I am aware of it, I notice it to some extent even in my cushion cut. But those broad table facets in the OECs seem to accentuate it. What causes this (ie, any way to tell from a stone's specs which stones might have it?). Many of the stones I have been looking at are rather deep.

I will try to post some photos showing my effort to capture the phenomenon with a camera (which was nearly impossible). In real life the shadowing is somewhat less, because instead of a big broad teal phone case three inches away, it's reflecting my skin and hair a bit further away. Anyway, any thoughts appreciated.
 

camomof4

Rough_Rock
Joined
Sep 5, 2015
Messages
64
Re: Table shadowing/obstruction in OECs (help, old cut exper

From a slight angle, no shadow

oec1.jpg

Head on, shadow



oec2_6.jpg
 

madelise

Ideal_Rock
Premium
Joined
Sep 23, 2011
Messages
5,362
Re: Table shadowing/obstruction in OECs (help, old cut exper

No that's not obstruction. That's literally your reflection, like you're describing. OECs tend to pick up color from its environment. That's why they turn pastel colors, or hot pink if you wear hot pink. If they never "moved" their facets, they would literally be a flat mirror.
 

camomof4

Rough_Rock
Joined
Sep 5, 2015
Messages
64
Re: Table shadowing/obstruction in OECs (help, old cut exper

Thanks M. Then can I expect to see this phenomenon in any diamond? And ... what is obstruction? :confused:
 

Michael_E

Brilliant_Rock
Trade
Joined
Nov 19, 2003
Messages
1,290
Re: Table shadowing/obstruction in OECs (help, old cut exper

Yes, you can see this in any diamond...if you get close enough. Move the stone towards and then away from you and you'll notice that the dark coloration will get small as the stone gets farther away. Head shadow, obstruction and reflection are all the same thing, a reflection of your head and upper body. Head shadow is a misnomer in that you can't see a shadow with a mirror, but only as a lack of reflection off of a non-reflective surface. Since a gem is just a fancy mirror, all you can see are reflections from different areas in front of the stone.
 

solgen

Brilliant_Rock
Joined
Apr 10, 2015
Messages
563
Re: Table shadowing/obstruction in OECs (help, old cut exper

I think it is obstruction. You're obstructing light entering the diamond. The man pav facets reflect your head or phone. OECs have wide mains so you may notice more obstruction than in a RBC with it's thinner arrows.
 

camomof4

Rough_Rock
Joined
Sep 5, 2015
Messages
64
Re: Table shadowing/obstruction in OECs (help, old cut exper

So would you say it's something to be concerned about if you see it in an OEC? Or just to be expected?
 

Diamond_Hawk

Brilliant_Rock
Trade
Joined
Apr 8, 2014
Messages
1,229
Re: Table shadowing/obstruction in OECs (help, old cut exper

camomof4,

camomof4 said:
So would you say it's something to be concerned about if you see it in an OEC? Or just to be expected?

All diamonds when viewed or photographed will have some type of obstruction. It is the nature of light and proportions in a diamond.

The place 'within' the diamond that shows obstruction will vary based on the angle of the viewer, the position of the diamond and the light source. As the diamond, light-source, or viewer angle is moved the areas that showed obstruction begin returning light to the viewer's eyes and other areas can show obstruction. This gives the facet patterns the "on/off" effect which results in light flashes.

How significant the obstruction is, and from what angle it is being viewed, can give each diamond a specific personality and can determine the scintillation effect as it moves through space and light.

One of the reasons many on this forum are fans of the Ideal-Scope and ASET images is the ability to see patterns of obstructions in a static environment.
 
Be a part of the community Get 3 HCA Results
Top