Find your diamond
Find your jewelry
shape
carat
color
clarity

Thoughts on this diamond? Mainly crown angle that makes me hesitate. 2.4 on the holloway cut advisor

Got any pics?
 
unfort that’s all I have. Nothing “professional”
 
I can’t tell you much of anything from those I’m afraid. It’s not a disaster but from the numbers I wouldn’t expect a disaster. How good is it? …
Is that your hand - have you seen it in-person?
 
over steep upper girdle facets, it is going to face up small in some lighting from lack of edge to edge brightness.
This angle combo can work with a smaller table or shorter stars or both but this one doesn't.
 
I think GIA rounding can make or break this stone. So ideal-scope or ASET images before I consider it
 
Karl_K said:
over steep upper girdle facets, it is going to face up small in some lighting from lack of edge to edge brightness.
This angle combo can work with a smaller table or shorter stars or both but this one doesn't.
Click to expand...

I understand the concern but I don’t see over darkness at the edges in those two pics though? Granted, they’re terrible pics so I don’t see much of anything.
 
yssie said:
I understand the concern but I don’t see over darkness at the edges in those two pics though? Granted, they’re terrible pics so I don’t see much of anything.
Click to expand...
based on the numbers there is a very strong indication it will be an issue, 80% of the upper girdle area is dark in the pictures.
The pics do suck but this is one where its an issue unless pictures show otherwise and they dont.
 
I’ve uploaded professional image of the diamond. Thank you for the comments so far. Diamond is $14700 for reference
 
Karl_K said:
yea upper girdles are pretty lifeless.
Click to expand...
I was going to say it is a good 36.5/40.6.
No twisted pavilion main, no detrimental girdle treatment. I guess the stone should look good under the ASET scope.

But I am not an expert in assessing upper girdle facet performance.
 
flyingpig said:
I was going to say it is a good 36.5/40.6.
No twisted pavilion main, no detrimental girdle treatment. I guess the stone should look good under the ASET scope.

But I am not an expert in assessing upper girdle facet performance.
Click to expand...
stop it face up and find the stars, then look at all the areas between the stars and girdle, lots of grey. Now start slowly moving the diamond paying attention to this area ignoring the rest of the stone still a lot of grey until it starts to flash latter than the rest of the diamond by a far margin.
 
Karl_K said:
virtual images that show it in terms of ASET
50% stars50stars.jpg
45% stars45stars.jpg
Click to expand...

Thanks for the ASETs.
For reasonably decently cut GIA EXs, I have only paid attention to painting/digging for assessing outer bezel performance.
 
Thanks @Karl_K. I just learned something new!
 
flyingpig said:
Thanks for the ASETs.
For reasonably decently cut GIA EXs, I have only paid attention to painting/digging for assessing outer bezel performance.
Click to expand...
With steep crowns and bigger tables it comes into play the steeper the crown(35+) the smaller the table needs to be unless the stars are short which produces longer shallower upper girdle facets.
In the past it did not come up much because such crowns were usually combined with deep pavilions and the hca rejected them to an extent they were outright rejected.
It comes up on oecs also, but the old time cutters knew about it and you will see a lot of short stars.

edit: 35/61t is where it gets bad at 35 degrees so arguably it could be said around 35.5 when you start checking for it with tables under 60. GIA rounding can change this of course.
 
Last edited:
Karl_K said:
With steep crowns and bigger tables it comes into play the steeper the crown(35+) the smaller the table needs to be unless the stars are short which produces longer shallower upper girdle facets.
In the past it did not come up much because such crowns were usually combined with deep pavilions and the hca rejected them to an extent they were outright rejected.
It comes up on oecs also, but the old time cutters knew about it and you will see a lot of short stars.
Click to expand...

This effect is rather similar to the center of a RBC turning ASET green when the pavilion angle drops below 40.7 degrees. So in that sense it is rather benign.
You are over shooting for a clean diamond Karl.
But once the diamond is dirty (like 99% of the time) then this stone will be dead as a dodo in the outer upper girdle facets.
 
Garry H (Cut Nut) said:
This effect is rather similar to the center of a RBC turning ASET green when the pavilion angle drops below 40.7 degrees. So in that sense it is rather benign.
You are over shooting for a clean diamond Karl.
But once the diamond is dirty (like 99% of the time) then this stone will be dead as a dodo in the outer upper girdle facets.
Click to expand...
I will take the second part as an agreement and not argue about the first.
 
Is the dimness or less saturated area of the red on the upper girdle area indicative of overall less brightness in the diamond and why an HCA notes diamonds cut like this as very good in brightness or am I reading into the image. I don’t see a lot of what I would call “in between,” or good not great ASET images. Just super and poor juxtaposed. Thank you pros for always teaching us something new.
 
AJ37 said:
Is the dimness or less saturated area of the red on the upper girdle area indicative of overall less brightness in the diamond and why an HCA notes diamonds cut like this as very good in brightness or am I reading into the image. I don’t see a lot of what I would call “in between,” or good not great ASET images. Just super and poor juxtaposed. Thank you pros for always teaching us something new.
Click to expand...
The green in the upper girdle area is an indication that can be confirmed with other images or in person viewing.
Some lighting and some angles can hide it some what but its one of those things that once you see it, then it becomes hard not to see it.

edit: it does not show well in an IS image being 2 colors it doesn't separate into as many zones.
 
Last edited:
Karl_K said:
The green in the upper girdle area is an indication that can be confirmed with other images or in person viewing.
Some lighting and some angles can hide it some what but its one of those things that once you see it, then it becomes hard not to see it.

edit: it does not show well in an IS image being 2 colors it doesn't separate into as many zones.
Click to expand...

If the stone is lose push it into some Plasticine and you will make it appear as it will when dirty
 
Karl_K said:
With steep crowns and bigger tables it comes into play the steeper the crown(35+) the smaller the table needs to be unless the stars are short which produces longer shallower upper girdle facets.
In the past it did not come up much because such crowns were usually combined with deep pavilions and the hca rejected them to an extent they were outright rejected.
It comes up on oecs also, but the old time cutters knew about it and you will see a lot of short stars.

edit: 35/61t is where it gets bad at 35 degrees so arguably it could be said around 35.5 when you start checking for it with tables under 60. GIA rounding can change this of course.
Click to expand...

Finally, this clears things up for me.

In the past, you have mentioned that 35.5+CA goes well with a smaller table. I did not understand this because steeper crowns match better with shallower pavilions, which combined with a smaller table can produce too much contrast (persistent elongated dark arrows). But there is the upper girdle angle and outer bezel performance that need to be considered.
 
flyingpig said:
which combined with a smaller table can produce too much contrast (persistent elongated dark arrows). But there is the upper girdle angle and outer bezel performance that need to be considered.
Click to expand...
It is all a balancing game.
80% actual lgf% is a real help also.
Garry and I have been talking a lot lately about viewing distances and that common systems are even more broken than we thought which is to heavy for this thread but is related to balancing one of these stones out.
 
You must log in or register to reply here.
GET 3 FREE HCA RESULTS JOIN THE FORUM. ASK FOR HELP
Jewelry Blog
PriceScope-Concierge-Ad
Find prime cuts.
Top