black spot in yellow diamond at certain angles

[GreenBling]

Sometimes I see a black spot shape of a small facet inside the diamond. But its only at certain angle. It comes and go. It's not an inclusion. So, can it be what PSers describe as leakage?

 

[chrono]

Are you able to capture this in a photograph? Or perhaps, find a picture showing this phenomena online?

 

[kenny]

Sometimes I see a black spot shape of a small facet inside the diamond. But its only at certain angle. It comes and go. It's not an inclusion. So, can it be what PSers describe as leakage?

Put the diamond in front of something large only one one color, say red.
If it's leakage that black spot will turn red.

If it's still black and you are positive it is not an inclusion, then it must be some dirt you need to clean off.

BTW clarity is only graded looking into the top of the diamond.
It is possible some inclusions that are not visible in the top view ARE visible from the side.
Such inclusions do not affect the clarity grade.

What is your diamond's clarity grade and who graded it? GIA? IGI? EGL? Vendor?

 

[GreenBling]

Are you able to capture this in a photograph? Or perhaps, find a picture showing this phenomena online?

http://www.youtube.com/watch?v=KLe4HesqfLU&feature=youtube_gdata_player

All diamonds in this clip has those black spots (maybe I'm using a wrong word to describe). The second one from the left, around 9 o'clock of the stone, see the black out space?

 

[GreenBling]

Sometimes I see a black spot shape of a small facet inside the diamond. But its only at certain angle. It comes and go. It's not an inclusion. So, can it be what PSers describe as leakage?

Put the diamond in front of something large only one one color, say red.
If it's leakage that black spot will turn red.

If it's still black and you are positive it is not an inclusion, then it must be some dirt you need to clean off.

BTW clarity is only graded looking into the top of the diamond.
It is possible some inclusions that are not visible in the top view ARE visible from the side.
Such inclusions do not affect the clarity grade.

What is your diamond's clarity grade and who graded it? GIA? IGI? EGL? Vendor?

It is set in a double halo with a YG basket so I can't really see through the stone. It is GIA VS2 and I've inspected it before set so am certain it's not inclusion. Is it because of how the light is being reflected? Have a feeling that it's not a good thing but that little black shade (ah, maybe this is a better word to describe it) actually adds some character and color to the yellow

 

[chrono]

Ah, definitely not an inclusion. I guess that can be considered light leakage because it is a function of the cut.

 

[minousbijoux]

Is that different than reflection? It just looks like reflection off the facet to me, but what do I know?!

 

[kenny]

I suspect dirt.

 

[chrono]

All right - the easiest thing to do first is have it undergo a good cleaning session to eliminate the possibility of it being dirty.

 

[GreenBling]

It's not dirt for sure. I bath my babies religiously I must apologize for my bad choice of the word 'spot' which is obviously misleading everyone.

Found an article that seems to explain the phenomenon I'm trying (unsuccessfully) to describe.

http://www.ruby-sapphire.com/brilliance_windows_extinction.htm

"Virtually all books on gem cutting describe brilliance and windows and all grading systems do the same. Extinction. however, is entirely absent from cutting treatises (Vargas,1969, Sinkankas,1984), and discussions of grading (Patterson, 1982; GIA, 1983; AGMS, 1986) have only recently mentioned the term. Even where mentioned, however, a true understanding of the cause and significance of extinction is not found.

The first mention of extinction found by the author in the literature is that of Patterson (1982). He states the following :

Black extinction is an often misunderstood characteristic of colored stones where black is reflected back instead of color. Wrongly, extinction is ignored, called tone, or called dichroism. It is a characteristic most commonly observed in Thai rubies and in sapphires from most sources. It will involve entire facet faces. As the stone is manipulated when face-up, the amount of extinction will remain relatively the same. The effect is also observed in some emeralds, often in tourmalines, many of the garnets, including tsavorite, and some spinels. For years the trade has called such stones "Garnety." It has been my experience that garnets and spinels which exhibit extinction also exhibit extensive anomalous double refraction. The characteristic appears to be a polarizing effect. Basically, a gem quality stone is 100% color and has no extinction. As extinction increases, value goes down more rapidly at first and then more slowly as black becomes a large part of the color. Extinction is a nonlinear effect, almost as strongly so as modifier (saturation).

The colored stone grading course workbook of the Gemological Institute of America (GIA, 1983) defines extinction in similar vague terms:

Extinction is areas of darkness visible when the stone is judged for brilliance. It is caused by blackness in the stone and the proportion angles. Judge extinction as a percentage or as a fraction of the whole stone. View the stone while holding it both horizontally and vertically and assess the extinction in whatever position it is the least.

The American Gem Market System (AGMS) Network Grading Manual (1986) had this to add about extinction:

"Extinction," or "blackout" in gem materials is a phenomenon most apparent in dark tone stones, but which can be present in lighter tone material also. The effect can be reduced in the middle of the stone by "windowing" during cutting. Orientation of rough during cutting can either decrease or increase the effect, but cannot entirely eliminate it unless the stone is cut too shallow or with almost no BRILLIANCE. When grading extinction, the stone is held face up over a plain white background under diffused daylight lighting, and a judgment is made as to how much (what percentage) of the stone reflects back the true color of the gem and does not "black out." The visible surface of the stone represents 100%. When the stone is tilted slightly in any direction, any extinction present will appear to move from facet to facet. The percentage of the stone which is "extinct" usually remains constant, so an estimation can be made as to what percent of the total area is extinctive. Care should be taken not to confuse dark tone with extinction. Extinction is black, with none of the hue of the stone apparent.""

 

[Fly Girl]

I was looking to replace my diamond and I remember seeing a stone and at some angles nearly a third of the stone would go black. I agree that it was extinction. It was a function of the cut of that particular diamond, and since I didn't think it was attractive, I didn't buy that diamond. The diamonds that I own now never have a big chuck go black at once, and I definitely prefer that.

 

[LD]

They are definitely areas of extinction. You see this quite a lot with yellow diamonds. Don't forget most are cut for colour rather than light performance. There's nothing that can be done other than a recut but unless there are a lot of areas like this I wouldn't be overly concerned.

 

[chrono]

I would not sweat it for that one occcasionally seen black/extinct facet. A recut is also not recommended since it is so minor, and also because FCDs are too few and costly for recuts.

 

[GreenBling]

now that I've learned about blackouts and what to look for, I found on my baby 2 when looking in from the sides and 1 on the top right quadrant . Lucky only at specific angles.

Thank you all for helping me find out what the blackout is all about. the more I learn about my baby's characteristics, the more I feel i truly OWN it