Education on the use of the HCA tool for super ideal cut diamonds

[Garry H (Cut Nut)]

Sorry still trying to get my head around it. So a diamond with a total depth of 61.5% wouldn’t be better than a diamond with a total depth of 62.2% in regards to having less dirt and grease?

I have two diamonds.
Diamond 1 is 35/40.8 57% 61.5%
Diamond 2 is 34.5/40.8 56% 62.6%

Diamond 1 is significantly better in performance, it seldom looks dirty and is always edge to edge sparkly.

Diamond 2 has poor performance not long after it’s cleaned, especially on the edges.

Both diamonds have great ideal scope images with no leakage.

@Garry H (Cut Nut) why would diamond 1 be a significantly better performer? It goes against what you have mentioned above?

Please forget about depth % totally and for ever Lanz.
Focus on the angles
if ideal perfect is 34.5 and 40.75 then 33.5 / 40.75 or 34.5 / 40.55 will show less gunk.
The gridle thickness is making up the difference in your 2 stones and we do not care about %'s. OK
Please - no more about 5's and focus on the angles which is where it is all at.
And light interacts with pavilion angles 5 times more than crown angles - hence the 5:1 ratio.

 

[lanz88]

Please forget about depth % totally and for ever Lanz.
Focus on the angles
if ideal perfect is 34.5 and 40.75 then 33.5 / 40.75 or 34.5 / 40.55 will show less gunk.
The gridle thickness is making up the difference in your 2 stones and we do not care about %'s. OK
Please - no more about 5's and focus on the angles which is where it is all at.
And light interacts with pavilion angles 5 times more than crown angles - hence the 5:1 ratio.

Thanks Garry, I’ll never mention depth percentage again haha. Diamond 1 girdle is medium and diamond 2 girdle is medium/slightly thick. Would LGF be making diamond 1 perform better than diamond 2? Diamond 1 is 75% and diamond 2 is 80%

 

[Garry H (Cut Nut)]

Sorry still trying to get my head around it!

I have two diamonds.
Diamond 1 is 35/40.8 57% 61.5%
Diamond 2 is 34.5/40.8 56% 62.6%

Diamond 1 is significantly better in performance, it seldom looks dirty and is always edge to edge sparkly.

Diamond 2 has poor performance not long after it’s cleaned, especially on the edges.

Both diamonds have great ideal scope images with no leakage.

@Garry H (Cut Nut) why would diamond 1 be a significantly better performer? It goes against what you have mentioned above?

GIA's rounding and a million other possabilities

 

[Garry H (Cut Nut)]

Thanks Garry, I’ll never mention depth percentage again haha. Diamond 1 girdle is medium and diamond 2 girdle is medium/slightly thick. Would LGF be making diamond 1 perform better than diamond 2? Diamond 1 is 75% and diamond 2 is 80%

Not to mention your vision, viewing distance and so on - the angular difference is hair splitting that GIA rounding can totally mess up.

 

[lanz88]

Not to mention your vision, viewing distance and so on - the angular difference is hair splitting that GIA rounding can totally mess up.

Thank you, this has all been very interesting and informative!! I thought getting a diamond with (on paper) perfect angles and a perfect ideal scope image would mean I was getting a beauty. But this diamond (number 2) loses all edge to edge sparkle not long after i clean it, so disappointing

 

[Garry H (Cut Nut)]

OK - share the two certs - one may be cloudy or hazy

 

[lanz88]

OK - share the two certs - one may be cloudy or hazy

Cool thanks! This is the cert for the diamond that underperforms

This is a photo of the underperforming diamond:

 

[Garry H (Cut Nut)]

The second stone grading report did not load, but that stone appears to have clouds. Different labs, insufficient info to make a judgement.
But with what I have - I suspect the clouds are your problem.
For example

 

[Garry H (Cut Nut)]

what was blacked out here?

 

[lanz88]

The second stone grading report did not load, but that stone appears to have clouds. Different labs, insufficient info to make a judgement.
But with what I have - I suspect the clouds are your problem.
For example

Omg thank you! Everyone has been calling me crazy but I could see that there was something wrong with it but I just didn’t know what because the numbers looked good as did the ideal scope

 

[Garry H (Cut Nut)]

if you have an Ideal-Scope image we might be able to see clouds that way too.
The hearts and arrows are useless for anything except symmetry.

 

[lanz88]

what was blacked out here?

The diamond that performs well is a lab diamond so I didn’t want to post the certificate in this forum incase I got in trouble…(I did post it but then I deleted it)

 

[lanz88]

if you have an Ideal-Scope image we might be able to see clouds that way too.
The hearts and arrows are useless for anything except symmetry.

This is the ideal scope image of the under performer.

 

[Garry H (Cut Nut)]

Not a professional photo - so no real help.
Not enough info to assist

 

[lanz88]

Not a professional photo - so no real help.
Not enough info to assist

Would a video help? I have a professional magnified video

 

[Garry H (Cut Nut)]

ok

 

[lanz88]

ok

https://imgur.com/a/3UQ7tbA

 

[Karl_K]

Edge to edge brightness problems are almost always a problem with the upper girdle facets.
In this case the upper girdle facets have significant it looks like digging.
Probably right on the edge of GIA giving it a hit.

 

[lanz88]

Edge to edge brightness problems are almost always a problem with the upper girdle facets.
In this case the upper girdle facets have significant it looks like digging.
Probably right on the edge of GIA giving it a hit.

Hi Karl, thanks for your input!! It’s greatly appreciated. Can I please ask what you mean by ‘probably right on the edge of GIA giving it a hit?’

 

[Karl_K]

Hi Karl, thanks for your input!! It’s greatly appreciated. Can I please ask what you mean by ‘probably right on the edge of GIA giving it a hit?’

eventually gia will downgrade to vg cut grade but problems can show up before that level is reached.

 

[lanz88]

eventually gia will downgrade to vg cut grade but problems can show up before that level is reached.

Would you say this is what has happened to my diamond?

‘Digging is usually done on diamonds where the rough dictated that the finished product would be deep. If a diamond measures 6.3 mm and there is enough room to have a 16% crown the cutter can dig the girdle from both sides (resulting in shorter lower girdle facets and longer stars) and saving the 1ct mark. The result is a smaller looking diamond with leakage around the edge. If the leakage is more than would help with contrast this was done for the sole purpose of maximizing the rough to hit a certain carat mark. Such diamonds are ‘cheated,’ and these are the diamonds to be cautious of. This treatment is visible in an ideal-scope’

 

[Karl_K]

Would you say this is what has happened to my diamond?

‘Digging is usually done on diamonds where the rough dictated that the finished product would be deep. If a diamond measures 6.3 mm and there is enough room to have a 16% crown the cutter can dig the girdle from both sides (resulting in shorter lower girdle facets and longer stars) and saving the 1ct mark. The result is a smaller looking diamond with leakage around the edge. If the leakage is more than would help with contrast this was done for the sole purpose of maximizing the rough to hit a certain carat mark. Such diamonds are ‘cheated,’ and these are the diamonds to be cautious of. This treatment is visible in an ideal-scope’

not exactly it has 80% gia rounded lowers which is long not short.
However it can be done to just the top.

 

[Diamond_Enthusiast]

Edge to edge brightness problems are almost always a problem with the upper girdle facets.
In this case the upper girdle facets have significant it looks like digging.
Probably right on the edge of GIA giving it a hit.

@Karl_K how could you tell that that the upper girdle facets have significant digging?

Is it from the areas in the photo between the arrows that look like the 3 degrees crown digging (enlarged green rectangle like areas) in column 1B of the table pasted from the link below?

https://www.pricescope.com/articles/visible_effects_painting_digging_superideal_diamonds

 

[lanz88]

not exactly it has 80% gia rounded lowers which is long not short.
However it can be done to just the top.

Thanks Karl, so in summary would you say that my diamond is underperforming and doesn’t have edge to edge brightness because of significant digging? Do you see any clouds that could be causing the issue like @Garry H (Cut Nut) mentioned?

 

[Karl_K]

Thanks Karl, so in summary would you say that my diamond is underperforming and doesn’t have edge to edge brightness because of significant digging? Do you see any clouds that could be causing the issue like @Garry H (Cut Nut) mentioned?

clouds big enough to cause major problems should be listed in the report in one way or another.

editing: would to should to more accurately reflect reality.

 

[Karl_K]

@Karl_K how could you tell that that the upper girdle facets have significant digging?

Is it from the areas in the photo between the arrows that look like the 3 degrees crown digging (enlarged green rectangle like areas) in column 1B of the table pasted from the link below?

https://www.pricescope.com/articles/visible_effects_painting_digging_superideal_diamonds

Not enough data to get a precise amount.
The edges of the photo are an indication but so are the IS images.
Its also one of those things that when you know what can cause the problem you start eliminating possibilities.

Edge brightness issues.
Did not trigger a GIA downgrade.
Worse when dirty so its a marginal case.
So what can happen with the upper girdles?
Well they can be to short making them steep but that would mean the stars would be long and or a large table. Stars are GIA rounded 50% and table is rounded 56%.
So that leaves painting or digging.
There is a lot of variation in the upper girdle region in images not accounted for by lighting.
Digging show effects with a lower amount of variation than painting.
So the most likely answer is digging.

 

[Diamond_Enthusiast]

Not enough data to get a precise amount.
The edges of the photo are an indication but so are the IS images.
Its also one of those things that when you know what can cause the problem you start eliminating possibilities.

Edge brightness issues.
Did not trigger a GIA downgrade.
Worse when dirty so its a marginal case.
So what can happen with the upper girdles?
Well they can be to short making them steep but that would mean the stars would be long and or a large table. Stars are GIA rounded 50% and table is rounded 56%.
So that leaves painting or digging.
There is a lot of variation in the upper girdle region in images not accounted for by lighting.
Digging show effects with a lower amount of variation than painting.
So the most likely answer is digging.

Thanks so much for explaining this! Very interesting to understand the thought process and logic!

 

[lanz88]

Not enough data to get a precise amount.
The edges of the photo are an indication but so are the IS images.
Its also one of those things that when you know what can cause the problem you start eliminating possibilities.

Edge brightness issues.
Did not trigger a GIA downgrade.
Worse when dirty so its a marginal case.
So what can happen with the upper girdles?
Well they can be to short making them steep but that would mean the stars would be long and or a large table. Stars are GIA rounded 50% and table is rounded 56%.
So that leaves painting or digging.
There is a lot of variation in the upper girdle region in images not accounted for by lighting.
Digging show effects with a lower amount of variation than painting.
So the most likely answer is digging.

Thank you so much for all this information Karl. It has really really helped!! For so long I’ve been trying to work out why it was so flat most of the time. I’m glad I finally know why! Btw, I’m going to tag you in another post

 

[lanz88]

@Karl_K , @Garry H (Cut Nut) - Would something like this (undisclosed digging) warrant a return of the diamond to the jeweller it was purchased from (bare in mind it was 2 years ago). I don’t wear the diamond because whenever I look at it it’s makes me sad because it doesn’t sparkle. Or it is it a too bad so sad kinda situation? If it was a customer of yours would you accept the diamond back for a trade or no?

 

[Karl_K]

@Karl_K , @Garry H (Cut Nut) - Would something like this (undisclosed digging) warrant a return of the diamond to the jeweller it was purchased from (bare in mind it was 2 years ago). I don’t wear the diamond because whenever I look at it it’s makes me sad because it doesn’t sparkle. Or it is it a too bad so sad kinda situation? If it was a customer of yours would you accept the diamond back for a trade or no?

Most jewelers would look at you like you have 4 heads and say its a gia EX.
Then they would clean it and say see its perfectly fine.
So it would depend on the stores trade in policy in general.