GIA Excellent Cut... Cut Advisor 5.8.. what to do??

[DIAOPPORTUNITY]

hey guys, i am looking at a

2.20 Round
F
SI2
vg/vg
excellent cut grade

Table 61%
depth 60.2%
crown 33.5%
pav 41.6%

My jewler says it looks beautiful and it has an excellent cut grade from gia on the cert but the cut advisor reads kinda poor at a score of 5.3. What are your thoughts? Can this stone still perform excellent optically even though the cut advisor''s score is 5.3?

 

[JulieN]

Pass.

Is it cheaply priced?

 

[Lorelei]

Date: 6/11/2008 4:40:33 PM
Author:DIAOPPORTUNITY
hey guys, i am looking at a

2.20 Round
F
SI2
vg/vg
excellent cut grade

Table 61%
depth 60.2%
crown 33.5%
pav 41.6%

My jewler says it looks beautiful and it has an excellent cut grade from gia on the cert but the cut advisor reads kinda poor at a score of 5.3. What are your thoughts? Can this stone still perform excellent optically even though the cut advisor's score is 5.3?

Welcome to Pricescope!

The HCA score could be because this diamond has a steep pavilion angle, the HCA can ding a diamond for this. Also GIA Excellent cut grade is broad, so you need to evaluate each diamond on it's own proportions, as some may perform better than others. The table is large on this diamond also, so unless you have seen it and love it, I would suggest looking for some others, also that pavilion angle could affect the diamond negatively. Cut is critical for a diamond's beauty, so it is well worth concentrating on. A good measurement for a pavilion angle can be between 40.6 and 41 degrees, coupled with a crown angle of 34 - 35 degrees, it is best to check carefully with the steeper and shallower ends of these proportions that they work in harmony for that particular diamond. Table measurements, some here prefer around 54 - 57 / 58%, polish and symmetry of very good and above.

If you are open to the idea of buying online, we could maybe suggest some diamonds which might suit you?

 

[honey22]

You can do a lot better IMHO.

 

[DIAOPPORTUNITY]

Date: 6/11/2008 4:44:16 PM
Author: Lorelei

Date: 6/11/2008 4:40:33 PM
Author:DIAOPPORTUNITY
hey guys, i am looking at a

2.20 Round
F
SI2
vg/vg
excellent cut grade

Table 61%
depth 60.2%
crown 33.5%
pav 41.6%

My jewler says it looks beautiful and it has an excellent cut grade from gia on the cert but the cut advisor reads kinda poor at a score of 5.3. What are your thoughts? Can this stone still perform excellent optically even though the cut advisor's score is 5.3?

Welcome to Pricescope!

The HCA score could be because this diamond has a steep pavilion angle, the HCA can ding a diamond for this. Also GIA Excellent cut grade is broad, so you need to evaluate each diamond on it's own proportions, as some may perform better than others. The table is large on this diamond also, so unless you have seen it and love it, I would suggest looking for some others, also that pavilion angle could affect the diamond negatively. Cut is critical for a diamond's beauty, so it is well worth concentrating on. A good measurement for a pavilion angle can be between 40.6 and 41 degrees, coupled with a crown angle of 34 - 35 degrees, it is best to check carefully with the steeper and shallower ends of these proportions that they work in harmony for that particular diamond. Table measurements, some here prefer around 54 - 57 / 58%, polish and symmetry of very good and above.

If you are open to the idea of buying online, we could maybe suggest some diamonds which might suit you?

I appreciate the feed back. This stone is being offered at 21,575. I have not seen this stone. I guess my question is; can it be possible for this stone to perform amazingly? Would you say i would have to compare this stone with a near perfect stone or H&A to determine if i can get better? How else would i really know if it is a dud? How else will i know if there is a better performer out there?

I am looking for a stone that will blind me when i see it.

 

[DIAOPPORTUNITY]

IMHO?

 

[strmrdr]

my 2c its a dud.
I wouldn''t buy a stone with that angle combination.

 

[JulieN]

Date: 6/11/2008 5:03:29 PM
Author: DIAOPPORTUNITY

I appreciate the feed back. This stone is being offered at 21,575. I have not seen this stone. I guess my question is; can it be possible for this stone to perform amazingly? Would you say i would have to compare this stone with a near perfect stone or H&A to determine if i can get better? How else would i really know if it is a dud? How else will i know if there is a better performer out there?

I am looking for a stone that will blind me when i see it.

Put a little lotion on your hands before you go into the jeweler. Put something black behind it (paper, your sleeve.) Close one eye. (Not something that's really fair, since you'll always have two eyes, you'll not see as many flashes) Ask yourself if you've been blinded by it.

Check out the videos on GOG (since it is a camera lens, it sort of stands in for one eye) and they're still quite nice looking.

Guerilla diamond-buying.

 

[Deelight]

Date: 6/11/2008 5:04:35 PM
Author: DIAOPPORTUNITY
IMHO?

IMHO= In my humble opinion

 

[Regular Guy]

Date: 6/11/2008 5:20:44 PM
Author: JulieN

Date: 6/11/2008 5:03:29 PM
Author: DIAOPPORTUNITY

I appreciate the feed back. This stone is being offered at 21,575. I have not seen this stone. I guess my question is; can it be possible for this stone to perform amazingly? Would you say i would have to compare this stone with a near perfect stone or H&A to determine if i can get better? How else would i really know if it is a dud? How else will i know if there is a better performer out there?

I am looking for a stone that will blind me when i see it.

Put a little lotion on your hands before you go into the jeweler. Put something black behind it (paper, your sleeve.) Close one eye. (Not something that''s really fair, since you''ll always have two eyes, you''ll not see as many flashes) Ask yourself if you''ve been blinded by it.

Check out the videos on GOG (since it is a camera lens, it sort of stands in for one eye) and they''re still quite nice looking.

Guerilla diamond-buying.

1) Julie, don''t stop posting.

2) Two systems for judging is not a lot (GIA & HCA). Be conservative. Get a green light on both (or...as you''ll see in item 3 below, use AGS instead of GIA)

3) For fun I looked for similar but different. Want to save 1/2?

 

[John P]

Date: 6/11/2008 4:40:33 PM
Author:DIAOPPORTUNITY
hey guys, i am looking at a

2.20 Round
F
SI2
vg/vg
excellent cut grade

Table 61%
depth 60.2%
crown 33.5%
pav 41.6%

My jewler says it looks beautiful and it has an excellent cut grade from gia on the cert but the cut advisor reads kinda poor at a score of 5.3. What are your thoughts? Can this stone still perform excellent optically even though the cut advisor's score is 5.3?

This kind of round brilliant make is called a 60-60; meaning table and depth both close to 60%.

There are some great 60-60s out there, but this is not likely to be one of them. The crown and pavilion angle combination will result in light "leaking" from the pavilion of the diamond. The GIA system is new (2006) and this first iteration allows some of these combos to be graded EX. This is why it's best to get "green lights" in a couple of systems, as was suggested.

For the record, as-regards this make: Some of the nicest 60-60s I have seen have PA close to 41 and CA at or below 34. Here are two ideal-scope simulations showing (broadly) what I'm talking about. The model on the left, using the basic numbers of the diamond discussed here, has a ring of white under the table where light entering the diamond is leaking out. The model on the left has better angles for this table-depth combo and is returning light with much greater efficiency. Note (as always) that these simulations assume perfect wire-frame symmetry which is impossible in real-life - and rarer in 60-60 makes than the near-Tolks we often see here.

 

[DIAOPPORTUNITY]

Date: 6/11/2008 5:51:20 PM
Author: John Pollard

Date: 6/11/2008 4:40:33 PM
Author:DIAOPPORTUNITY
hey guys, i am looking at a

2.20 Round
F
SI2
vg/vg
excellent cut grade

Table 61%
depth 60.2%
crown 33.5%
pav 41.6%

My jewler says it looks beautiful and it has an excellent cut grade from gia on the cert but the cut advisor reads kinda poor at a score of 5.3. What are your thoughts? Can this stone still perform excellent optically even though the cut advisor''s score is 5.3?

This kind of round brilliant make is called a 60-60; meaning table and depth both close to 60%.

There are some great 60-60s out there, but this is not likely to be one of them. The crown and pavilion angle combination will result in light ''leaking'' from the pavilion of the diamond. The GIA system is new (2006) and this first iteration allows some of these combos to be graded EX. This is why it''s best to get ''green lights'' in a couple of systems, as was suggested.

For the record, as-regards this make: Some of the nicest 60-60s I have seen have PA close to 41 and CA at or below 34. Here are two ideal-scope simulations showing (broadly) what I''m talking about. The model on the left, using the basic numbers of the diamond discussed here, has a ring of white under the table where light entering the diamond is leaking out. The model on the left has better angles for this table-depth combo and is returning light with much greater efficiency. Note (as always) that these simulations assume perfect wire-frame symmetry which is impossible in real-life - and rarer in 60-60 makes than the near-Tolks we often see here.

Amazing John, that was the response i was looking for. Thanks so much for your detailed explanation.

Do you think this is great price?

 

[John P]

Date: 6/11/2008 6:20:35 PM
Author: DIAOPPORTUNITY

Amazing John, that was the response i was looking for. Thanks so much for your detailed explanation.

Do you think this is great price?

You're welcome. My pleasure.

Ask yourself what is most important about the diamond you want: Size? How well it sparkles? No tint? Free of inclusions?

If how it sparkles is #1 or #2 (as it is for most people) I'd suggest you keep looking.

Price: $21.5K is a few thousand dollars more than comparable 60-60s you can find by using the search engine on this site. Have you used it to explore? You can find near-Tolkowsky makes under that price as well, if it's of interest to you.

 

[diamondseeker2006]

Here is a better cut 2.07 G SI1 for $19,370. Ask if it is eye clean.

http://www.jamesallen.com/diamonds/G-SI1-Ideal-Cut-Round-Diamond-981003.asp?b=16&a=12&c=77&cid=131

 

[Lorelei]

Sir John, I am just curious, that a diamond with the above proportions is still considered to be a 60 60? I thought if one of the proportions for d and t hit 61% then it wouldn't, please edumacate me!

Diaop, take a look at the diamond DS posted above, that could be a far better choice for you.

 

[John P]

Date: 6/12/2008 5:46:10 AM
Author: Lorelei

Sir John, I am just curious, that a diamond with the above proportions is still considered to be a 60 60? I thought if one of the proportions for d and t hit 61% then it wouldn't, please edumacate me!

Happy to comment, M'Lady. Not everything is subject to that tendency towards precision (OCD?) we have on PS. 60-60 is a descriptor like near-Tolkowsky. It’s a convenient way to refer to a certain look, like “shallow” or “steep/deep” or FIC and BIC.

In GIA terms 53-59% tables are small, 60-64% are medium and 65%+ are large. I consider diamonds centered in their medium table range to be 60-60 when depth is 59-62ish, because those makes usually have a similar overall "look" (not talking about performance level).

 

[Lorelei]

Date: 6/12/2008 9:39:24 AM
Author: John Pollard

Date: 6/12/2008 5:46:10 AM
Author: Lorelei

Sir John, I am just curious, that a diamond with the above proportions is still considered to be a 60 60? I thought if one of the proportions for d and t hit 61% then it wouldn''t, please edumacate me!

Happy to comment, M''Lady. Not everything is subject to that tendency towards precision (OCD?) we have on PS. 60-60 is a descriptor like near-Tolkowsky. It’s a convenient way to refer to a certain look, like “shallow” or “steep/deep” or FIC and BIC.

In GIA terms 53-59% tables are small, 60-64% are medium and 65%+ are large. I consider diamonds centered in their medium table range to be 60-60 when depth is 59-62ish, because those makes usually have a similar overall ''look'' (not talking about performance level).

Merci beaucoup Monsieur!

 

[DIAOPPORTUNITY]

I just recieved another cert, seems to be another 60-60. It scores worse on the HCA.

2.54ct
I
SI1

table- 60
depth-60
crown- 32
pav-41.8

This stone is also graded GIA ex/ex and excellent cut.

John, this stone seems to be in the parameters you were describing as a nice 60-60. Can it be that all 60-60's do not score well on the HCA but can still perform like a Tolks?

 

[DIAOPPORTUNITY]

I have been doing some research and watched some videos on GOG, what is gridle facet length? Is this important to keep in mind? How do you find out what a particular stone''s GFL is?

 

[lovehersomuch]

pass on this stone.. 21k is too much.. my stone got a 1.3 on the HCA and is an excellent cut

 

[strmrdr]

Date: 6/12/2008 10:09:04 AM
Author: DIAOPPORTUNITY
I just recieved another cert, seems to be another 60-60. It scores worse on the HCA.


2.54ct

I

SI1


table- 60

depth-60

crown- 32

pav-41.8


This stone is also graded GIA ex/ex and excellent cut.


John, this stone seems to be in the parameters you were describing as a nice 60-60. Can it be that all 60-60''s do not score well on the HCA but can still perform like a Tolks?

It is worse than the other one.
The hca does a pretty good job of sorting out crown/pavilion angle combinations.
A pavilion that deep is not going to be a good performer.

A 60-60 has its own look and wont look like a near tolk.
A great one can have as much performance but a different look in a lot of lighting conditions.

 

[strmrdr]

Date: 6/12/2008 10:12:22 AM
Author: DIAOPPORTUNITY
I have been doing some research and watched some videos on GOG, what is gridle facet length? Is this important to keep in mind? How do you find out what a particular stone's GFL is?

lower girdle facet percentage is on the newer reports from GIA and AGS.
This page has more information:
http://goodoldgold.com/Articles/MinorFacets/

 

[Fly Girl]

Date: 6/12/2008 11:30:01 AM
Author: strmrdr

Date: 6/12/2008 10:09:04 AM
Author: DIAOPPORTUNITY
I just recieved another cert, seems to be another 60-60. It scores worse on the HCA.


2.54ct

I

SI1


table- 60

depth-60

crown- 32

pav-41.8


This stone is also graded GIA ex/ex and excellent cut.


John, this stone seems to be in the parameters you were describing as a nice 60-60. Can it be that all 60-60''s do not score well on the HCA but can still perform like a Tolks?

It is worse than the other one.
The hca does a pretty good job of sorting out crown/pavilion angle combinations.
A pavilion that deep is not going to be a good performer.

A 60-60 has its own look and wont look like a near tolk.
A great one can have as much performance but a different look in a lot of lighting conditions.

Agreed. I have a 1.5 ct 60/60 diamond that was hand picked for me 8 years ago, well before the HCA and Pricescope. It scores 2.6-2.8 on the HCA, and is very nice performer. I get lots of compliments.

The HCA does a nice job of weeding out the duds. Keep looking. Try to find a stone that scores below 3 on the HCA before bringing it in. Two or below is best.

 

[DIAOPPORTUNITY]

Does anyone have any aset images or links to a good 60-60, i want to understand the different look everyone is talking about. Can anyone describe this look? Large facets, small facets, old world...etc

 

[John P]

Date: 6/12/2008 10:09:04 AM
Author: DIAOPPORTUNITY
I just recieved another cert, seems to be another 60-60. It scores worse on the HCA.

2.54ct
I
SI1

table- 60
depth-60
crown- 32
pav-41.8

This stone is also graded GIA ex/ex and excellent cut.

John, this stone seems to be in the parameters you were describing as a nice 60-60. Can it be that all 60-60''s do not score well on the HCA but can still perform like a Tolks?

Ay Caramba (see highlighted).

No one proportion can define a diamond, it must be taken as a whole, but in this case you have a pavilion angle that is out of bounds for the attractive rounds I''m accustomed to.

The pavilion angle is what many consider the most critical element. In the most popular metrics discussed here - AGS, GIA, HCA and AGA - pavilion angles 40.6 - 41.0 have the greatest approval cross-system. There are exceptions but that range is a good starting place for discussion. AGS shows most 0 light performance candidates to be in that range. The HCA and AGA prefer the shallow side (and a bit lower). GIA prefers the steeper side (and higher). If you were wondering, this is why the GIA gives EX to steep diamonds the HCA rejects and the HCA gives thumbs-up to shallow diamonds the GIA system doesn''t reward.

I give the pavilion as an example because the diamond cutters I learn from consider the pavilion mains the engine that is driving light return. Pursuing that thought, yes, the lower halves (aka lower girdle facets/LGF) are important, but the pavilion is Batman. The lower halves are Robin. Batman is more important. He is the icon. He can kick butt on his own. Robin makes him complete and is crucial to the whole story but don''t think for a minute he can do it all himself.

Can anyone tell it''s late and I am tired?

Here is a recent thread about Robin, err, lower halves: https://www.pricescope.com/community/threads/how-does-lower-girdle-length-affect-face-up-performance.87181/ Don''t read too much into it. If you''re wanting a table near 60% a lot of the diamonds manufactured will have lower halves near 80%.

I don''t know that you ever said why you are looking for a 60/60 make specifically (?) Have you looked at near-Tolkowsky rounds?

 

[John P]

Date: 6/12/2008 11:50:38 AM
Author: DIAOPPORTUNITY

Does anyone have any aset images or links to a good 60-60, i want to understand the different look everyone is talking about. Can anyone describe this look? Large facets, small facets, old world...etc

A great ASET image will look similar in any round. It tells about the diamond's overall performance (mostly about its brightness and contrast) so you'll see mostly red with a nice balance of blue and some green, regardless of make.


The differences between equally performing 60-60, near-Tolk and high-crowned configurations often have to do with the mix of brightness and fire visible in their performance qualities. Read the HCA information here. Here are two examples of how different mixes of brightness and fire can be acquired.

Example 1: The inverse crown and pavilion angle relationship

If you look at the pavilion range mentioned in the last post (40.6 - 41.0) and go from left to right you will see the most complimentary crown angles for that range are around 33-35 degrees. As you move from left to right on the scale the crown height is increased (because you are making the crown angle steeper) and you move subtly from more brightness towards more fire. Remember that this entire chart is for diamonds with 57% tables. To change the mix of fire and brightness we're changing the angles.

Example 2: Table Size

Now lets keep the angles the same and alter table% to change the mix.

I was discussing this very thing with a lovely lady in Houston earlier today.

Permit a broad generalization that's not as informative or germane as the chart above (but it's fast and easy!).

I've kept the crown and pavilion angles identical for the three sims below (40.7/34.5).
The tables go from 50% to 55% to 60%. Nothing else changes.
As you can see, with all else equal, a larger table results in a lower crown height.

Diamond 1 has a very small table, 50%. The crown is quite high at 17%. The HCA would place this near "More Fire" but I think it would be penalized for spread; with so much weight in the crown it would appear a little smaller than it should. Few diamonds are cut this way. Cartier & Tiffany do cut a number of their diamonds to the "high crowned" side of near-Tolk...but not as dramatic as this model with the 50% table. They finish with near-Tolk tables but steeper crown angles that result in crown heights near 16% or so.

Diamond 2 is a near-Tolkowsky make. The crown height is in the 15% range. The HCA places it in the middle of fire & brightness. Many top brands and signature/non-branded H&A type cuts you often see on Pricescope fall into this category. There is usually more weight lost when cutting a diamond to near-Tolk angles, especially if you're going for patterning/precision, so they are nowhere near as abundant as 60-60 or steep-deeps.

Diamond 3 is a 60-60. Crown height is 13.5%. The HCA would place this near "More Brightness." With these angles it would be a rocking 60-60. However, many of the 60-60s out there have pavilions deeper than this and crowns that are shallower, so the "spready look" is exaggerated and when those pavilions go above 41 they can leak light. Abundant diamonds are made this way because in many situations it's the most prudent shape to recover weight from the rough, which is always the goal. In that sense, pieces of rough which lend themselves to deep pavilion, low crown, spready-table stones are more abundant than pieces which finish best as examples 1 or 2. There are true 60-60 gems out there (Fly Girl has one and I know trade members who prefer this look when performance is tops) but if you jump into the mainstream market you will generally have to do some panning to find one with killer crown and pavilion angles. If the spready and bright look is what you prefer it's worth the time to do it.

A steep-deep make is one with steep pavilion and crown angles. The extreme is the nailhead. These diamonds leak light, hide weight and can entrap color. There are also shallows. Not as evil as the steep-deep but subject to their own issues of durability, darkness or fisheye. Don't worry. The PS crowd will typically ID any such varmints and tell you to run.

 

[John P]

By the way, all the above diamonds score under 2 on HCA.
They are all predicted to get AGS0 light performance (number 3 is borderline)
Number 2 and number 3 receive GIA EX in facetware (number 1 receives VG)

Given nice cut precision and appropriate minor facets I’d have a blast with any of them.

 

[Dancing Fire]

my next RB will be a high crown with small table like 53-54%,but they don''t cut many with small tables.

 

[John P]

Date: 6/13/2008 11:28:14 AM
Author: Dancing Fire
my next RB will be a high crown with small table like 53-54%,but they don't cut many with small tables.

I love them DF. If you want to maximize that look have you considered an antique cut rather than a RB?

This is quite simplified, but illustrates how a piece of sawable rough octahedron can be planned to yield two diamonds. If you make the crowns higher more of the rough is wasted. Larger tables/lower crowns and deep pavilions often maximize weight recovery.

 

[DIAOPPORTUNITY]

thanks for all the info, your expertise is awesome.