Oh No, dirty diamonds - why Cut is REALLY important

[Garry H (Cut Nut)]

Both diamonds weigh one carat each and are within a color and clarity grade.

In the top picture taken on grey card board - the slightly shallow Ideal Cut diamond on the right has a bigger diameter than the dog on the left. But if you knew nothing and all the diamonds in a store looked like this one you might never know the difference.

In the lower photo both diamonds have been pushed into bees wax to make them dirty (but only their pavilions - the tableshave been wiped and are as clean as I could make them.

Now the diamond on the right looks much bigger, and still has much of its sparkle, but the below average diamond on the left has lost its sparkle and you can see the bee’s wax through it.

 

[DBM]

Gary what is the depth and girdle thickness of the one on the left?

 

[HooCares]

I am curious--what are the diameters for both of the stones?

 

[starryeyed]

Wow, FASCINATING!! Not to be gross, but in real life this happens - like if you don''t take your studs out for a week or if your ring setting collects residue easily. This is a very REAL problem and your study shows the phenomena in a cool scientific way. Thanks!

 

[oldminer]

I think Garry is using a rather unusual thinner "ideal" cut as the large diamoeter example stone. I agree that with such a stone the wax won''t have a huge effect, but on a more typical, less well cut thin stone, the wax would have a drastic effect great than that shown on the deep stone.

Maybe Garry will come back to this thread and tell us about the experiment. I know Garry has created a good inventory of diamond in his own store using the Ideal-Scope techniques which allow some thinner, high performance stones to be very useful and good for his inventory. Let''s see what Garry tells us.

 

[Garry H (Cut Nut)]

Date: 11/22/2006 12:05:26 PM
Author: oldminer
I think Garry is using a rather unusual thinner ''ideal'' cut as the large diamoeter example stone. I agree that with such a stone the wax won''t have a huge effect, but on a more typical, less well cut thin stone, the wax would have a drastic effect great than that shown on the deep stone.

Maybe Garry will come back to this thread and tell us about the experiment. I know Garry has created a good inventory of diamond in his own store using the Ideal-Scope techniques which allow some thinner, high performance stones to be very useful and good for his inventory. Let''s see what Garry tells us.

Here is the Gem Adviser model for the bad stone.
DMB it weighs 1.01ct and spreads 5.86mm. The girdle is like a tractor tire and you can see from the DiamCalc light return etc that it performs about the same as a average princess cut (but with a way smaller spread (-35%).

I have not scanned the nice shallower stone yet - I will later today (it is 6.15am here).

 

[Garry H (Cut Nut)]

Date: 11/22/2006 12:05:26 PM
Author: oldminer
I think Garry is using a rather unusual thinner ''ideal'' cut as the large diamoeter example stone. I agree that with such a stone the wax won''t have a huge effect, but on a more typical, less well cut thin stone, the wax would have a drastic effect great than that shown on the deep stone.

Maybe Garry will come back to this thread and tell us about the experiment. I know Garry has created a good inventory of diamond in his own store using the Ideal-Scope techniques which allow some thinner, high performance stones to be very useful and good for his inventory. Let''s see what Garry tells us.

Actually this is not a shallow stone - just a boring old TIC (T57.6 C34.86 P40.91) unpainted 3.1% girdle at mains 1.49% at valley. B grade H&A''s

Here is its Gem Adviser model.

 

[DBM]

5.86 mm !! were you out to look for the heaviest 1 carater you could find ??

the depth would probably be something like 68 if not for the very thick girdle, no?

 

[Garry H (Cut Nut)]

Date: 11/22/2006 8:41:57 PM
Author: DBM
5.86 mm !! were you out to look for the heaviest 1 carater you could find ??

the depth would probably be something like 68 if not for the very thick girdle, no?

72.1%
We use it as an example to frighten people DBM
But despite the thick girdle, and the chaotic symmetry, I see a lot of diamonds with more leakage as you can see in the gem adviser file

 

[kenny]

Any more leakage and the diamond would have to be made of swiss cheese.

 

[DBM]

72.1%
We use it as an example to frighten people DBM
But despite the thick girdle, and the chaotic symmetry, I see a lot of diamonds with more leakage as you can see in the gem adviser file

72.1%
We use it as an example to frighten people DBM -- naughty, naughty. no wonder why everyone hear is obsessed about Cut

But despite the thick girdle, and the chaotic symmetry, I see a lot of diamonds with more leakage as you can see in the gem adviser file -- yes i''ve seen this (albeit not on a diamond like a 72.1 which i''ve never seen before). Actually I find that the depth of stones sometimes helps in the faceup color , do you find that as well or am i mistaking the cause for something else??...

 

[Garry H (Cut Nut)]

Date: 11/22/2006 9:40:51 PM
Author: kenny
Any more leakage and the diamond would have to be made of swiss cheese.

Actually this is only a slightly steep deep stone.
It is not very leaky - some GIA Excellent and Very Good steep deeps will look nearly this bad

 

[Garry H (Cut Nut)]

Date: 11/22/2006 9:45:03 PM
Author: DBM
yes i''ve seen this (albeit not on a diamond like a 72.1 which i''ve never seen before). DBM I just searched and found 5 pages of rounds with depths greater than 70% - there are plenty about - but most never get certified
Actually I find that the depth of stones sometimes helps in the faceup color , do you find that as well or am i mistaking the cause for something else??...

 

[DBM]

Date: 11/22/2006 10:03:45 PM
Author: Garry H (Cut Nut)

Date: 11/22/2006 9:45:03 PM
Author: DBM
yes i''ve seen this (albeit not on a diamond like a 72.1 which i''ve never seen before). DBM I just searched and found 5 pages of rounds with depths greater than 70% - there are plenty about - but most never get certified
Actually I find that the depth of stones sometimes helps in the faceup color , do you find that as well or am i mistaking the cause for something else??...

Please call me Daniel. So do you find that the faceup color improves with greater depth?

 

[Garry H (Cut Nut)]

Date: 11/22/2006 10:56:32 PM
Author: DBM

Please call me Daniel. So do you find that the faceup color improves with greater depth?

Sorry Daniel, I did not answer that part.
This diamond would (and does) show more face up color because

1. it has very little contrast. A star pattern of arrows creates more contrast that makes a round brilliant look brighter.

2. this stone has poor light return - therefore you can see more of the body color. We had Marc Brauner, director of IGI, tell us their rules for grading color earlier this year on the forum. They look at stones face up when they are border line calls - typically a well cut round could be bumped up and say a radiant migh be dropped a grade. Sometimes people in the market will say IGI is soft on color - but in fact this is a common sense approach and is user focused (but then common sense is not common)

edited later to add 3. the third factor is ray path length. A well cut round has a lot of in, bounce off alternate pavilion facets and wammy - out the crown or table. This short and direct light path means less color is picked up along the way compared to a radiant or poorly cut round that might have many ray paths that are twice or 3 times longer. If some of those rays do not come out the top again - then you are looking into exaggerated color space.

 

[Garry H (Cut Nut)]

The non leaky stone Hearts

 

[Garry H (Cut Nut)]

ASET

 

[Garry H (Cut Nut)]

Ideal-scope

 

[etienneperret]

Keep them Clean!
This just goes to show how important it is to keep ones diamonds clean. It is amazing how we wash our $5 underwear daily, yet so many people seldom clean their $5000 diamonds. Just keeping ones diamond clean gives it the appearance that is as good as a diamond several grades higher that has not seen a cleaner in months.
So keep ''em clean and dazzle your friends!

 

[diamondhunter10]

Gary, Great information, I thought that was rather interesting about the subtle Cut and the differences.
I guess I learned my "something new " today

 

[Garry H (Cut Nut)]

Date: 11/23/2006 2:34:57 PM
Author: etienneperret
Keep them Clean!
This just goes to show how important it is to keep ones diamonds clean. It is amazing how we wash our $5 underwear daily, yet so many people seldom clean their $5000 diamonds. Just keeping ones diamond clean gives it the appearance that is as good as a diamond several grades higher that has not seen a cleaner in months.
So keep ''em clean and dazzle your friends!

Of course that is the answer Etienne, but it obviously helps heaps if the stones are clean.

Here is the ideal-scope

Had a bit on and have been taking the pic''s as I have time

 

[Garry H (Cut Nut)]

Date: 11/23/2006 3:13:06 PM
Author: diamondhunter10
Gary, Great information, I thought that was rather interesting about the subtle Cut and the differences.
I guess I learned my ''something new '' today

Thanks DHunter, glad you are getting something out of it.

Lots of reads - but very few comments.

Time I threw in a bomb or two?

I would love there to be an option o "apply" virtual dirt to the pavilion only of diamonds in DiamCalc - it will throw a whole new aspect on the issue.

I have for a very long time predicted that my shallower preferences will be found to be "where it is at".

 

[HooCares]

I''ve had a question on my mind for a while and I wonder if it is related to this thread. I have a diamond that is 5.4 mm in diameter (.60 carat). It is an ideal cut H&A. I have seen some .50 carat stones (cut unknown) that look larger than my .60 carat one, even one that was 5.3 mm in diameter. I understand that stones can look larger because their cut is shallower, and I am very happy with my better cut stone and would not trade it in for a lower cut. But for my understanding, how can a lower carat weight, smaller diameter stone look larger than an ideal cut, larger diameter stone (other than the perhaps the setting it is placed in)? Does table size play a part? What might be the other factors if any?

 

[aljdewey]

Date: 11/24/2006 12:02:25 AM
Author: Garry H (Cut Nut)

Thanks DHunter, glad you are getting something out of it.

Lots of reads - but very few comments.

Garry, that''s probably because the message isn''t especially suited to the average PS audience.

At PS, you''re speaking to a group of folks who are obsessive to the point of near psychosis about their diamonds......as in, the type of folks who are ANAL about keeping diamonds clean! So, telling such a group why a shallow diamond is better for those who like to wear them dirty really doesn''t resonate to folks who wouldn''t dream of walking around with a filthy stone.

Your message is great for the masses, but it kinda misses the mark for the average anal PSer.

 

[diamondseeker2006]

I''d agree with Alj in that the comparison is a no brainer because none of us would ever even consider a stone that bad. I''d much rather see a comparison of a very good cut with and ideal cut stone. That would be interesting to me.

 

[JohnQuixote]

Date: 11/22/2006 10:56:32 PM
Author: DBM

Date: 11/22/2006 10:03:45 PM
Author: Garry H (Cut Nut)

Date: 11/22/2006 9:45:03 PM
Author: DBM
yes i've seen this (albeit not on a diamond like a 72.1 which i've never seen before). DBM I just searched and found 5 pages of rounds with depths greater than 70% - there are plenty about - but most never get certified
Actually I find that the depth of stones sometimes helps in the faceup color , do you find that as well or am i mistaking the cause for something else??...

Please call me Daniel. So do you find that the faceup color improves with greater depth?

Greater depth will increase the perceived body color. Fancy colored round diamonds are often cut deeper than conventional D-Z colors because they don't return as much light, entrapping body color. The reduction of brilliance, dispersion and scintillation also makes that body color more visible.

Nice topic Garry. Good inspiration for holiday shopping; jewelry cleaner stocking stuffers.

 

[Garry H (Cut Nut)]

Date: 11/24/2006 9:23:23 AM
Author: HooCares
I''ve had a question on my mind for a while and I wonder if it is related to this thread. I have a diamond that is 5.4 mm in diameter (.60 carat). It is an ideal cut H&A. I have seen some .50 carat stones (cut unknown) that look larger than my .60 carat one, even one that was 5.3 mm in diameter. I understand that stones can look larger because their cut is shallower, and I am very happy with my better cut stone and would not trade it in for a lower cut. But for my understanding, how can a lower carat weight, smaller diameter stone look larger than an ideal cut, larger diameter stone (other than the perhaps the setting it is placed in)? Does table size play a part? What might be the other factors if any?

There were (and still can be today) many diamonds given AGS ideal that were good examples of bad ''ideal cut'' and H&A''s under their old grading report that does not use their light performance system.
Dealers can still have these old reports issued.

This is an image of one from some years back where we became aware of this fact that AGS were grading what we call Dug Out upper girdle facets. This definetly reduces the light return at and near the stones edges and makes the stone look smaller.

Conversely the stone you compared might have been painted - which is the oppposite effect and improves edge brightness with the right proportions etc

Tabl has little effect.

 

[yellowsparkles]

This is a very interesting topic.

How does this apply to fancy cuts? I have a cushion that I am considering trading up (better / bigger). It has always bothered me that the stone does not look very good when dirty. I love my "mr clean", but seriously, I would think it should look better at the end of the day. I was more concerned with color than cut when I bought the stone. But now I am wanting a better cut.

How can we find the ideal cut cushion when it doesn''t exist? Or does it?

 

[diamondsrock]

I'm going to go totally against the grain here. The h&a on the right is lovely and would of course be my pick out of the two.
However, in the bottom photo, I swear it looks more dirty than the poorly cut stone. Cloudy, hazy, spotty. The one on the left has major leakage through the bottom and isn't cut as well, but I'm not seeing the cloudiness that I do on the h&a in that bottom picture. What am I missing here? Do you see what I mean from the photo?

 

[Garry H (Cut Nut)]

Date: 11/24/2006 6:10:30 PM
Author: yellowsparkles
This is a very interesting topic.

How does this apply to fancy cuts? I have a cushion that I am considering trading up (better / bigger). It has always bothered me that the stone does not look very good when dirty. I love my ''mr clean'', but seriously, I would think it should look better at the end of the day. I was more concerned with color than cut when I bought the stone. But now I am wanting a better cut.

How can we find the ideal cut cushion when it doesn''t exist? Or does it?

Don''t hold your breath.
f you like the crushed ice effect - then you will need to live with more of a see thru effect.
Also Radiant and to some extent cushions show more color - stay above G