help me to choose diamond, thank you

[dicxz80]

Dear all,

please kindly help to choose between these two diamond, need to decide within hours before they release hold, this diamond is from james allen

I am trying to do my self learning, but still can't decide

diamond A

0.71, H, VS1, EX-EX-EX
HCA score : 1.3 (based on GIA)
HCA score : 2.2 (based on Sarin Average)

diamond B

0.77, I, VS2, EX-EX-EX
HCA score : 1.9 (based on GIA)
HCA score : 1.8 (based on Sarin Average)

my question
1. why for diamond A , HCA score is so much different when using GIA stats and Sarin average stats
2. from the IS image, diamond B picture looks "pale" compare to diamond A, does it mean that it is less "sparkle" less "brilliant" less "returned light?"
3. what is Star/Upper ratio ? is it ok if the Star% is less ? most of the time I see in Sarin report for other diamond Star% is higher

my concern
1. diamond B is cheaper by 2xx USD (PROS)
2. diamond B is bigger (PROS)
3. diamond B is having "thicker" girdle (does this affect fire, brilliance, scintillation, and brightness ??) cant get information from the net (CONS)
4. both looks clean, under JamesAllen magnifier loupe
5. diamond B looks "cleaner" based on IS image (PROS) based on my own newbie eye
6. diamond B IS image looks "pale" compare to diamond A (CONS)

Note
1. truthaboutdiamond.com recommend me diamond B because it is more "valuable" for money, bigger carat weight
2. jamesallen give this comment through email when they send Sarin report

We'll also taken the liberty of having these diamonds inspected by one of our graduate gemologists and they had some great things to say about diamond A (0.71crt H VS1)! It has great fire, brilliance, and scintillation and appears exceptionally bright. It's eye clean, has a true "H" color, and an excellent cut.

Diamond B (0.77crt I VS2) is eye clean, has a true "I" color, and is also very bright. The trained eye of the gemologist saw diamond A is slightly brighter.

While both of your selections are great, diamond A is our gemologist's favorite since it's a little bit brighter and since it has a higher color.

out of topic question/comment from me
1.james allen sarin report is not detail
2.blue nile doesn't provide Sarin report / IS image

Thank you in advance !

 

[dicxz80]

additional information

diamond A GIA report stats

ROUND BRILLIANT

Measurements: 5.73 - 5.76 x 3.57 mm
Carat Weight: 0.71 carat
Color Grade: H
Clarity Grade: VS1
Cut Grade: Excellent
PROPORTIONS

Depth: 62.0%
Table: 55%
Crown Angle: 34.5°
Crown Height: 15.5%
Pavilion Angle: 40.8°
Pavilion Depth: 43.0%
Star Length: 45%
Lower Half: 75%
Girdle: Medium to Slightly Thick, Faceted (3.5%)
Culet: None

FINISH
Polish: Excellent
Symmetry: Excellent
Fluorescence: None

CLARITY CHARACTERISTICS
Cloud, Needle




diamond B GIA report stats

ROUND BRILLIANT

Measurements: 5.85 - 5.86 x 3.66 mm
Carat Weight: 0.77 carat
Color Grade: I
Clarity Grade: VS2
Cut Grade: Excellent
PROPORTIONS

Depth: 62.5%
Table: 55%
Crown Angle: 34.5°
Crown Height: 15.5%
Pavilion Angle: 41.0°
Pavilion Depth: 43.0%
Star Length: 50%
Lower Half: 75%
Girdle: Medium to Slightly Thick, Faceted (4.0%)
Culet: None

FINISH
Polish: Excellent
Symmetry: Excellent
Fluorescence: None

CLARITY CHARACTERISTICS
Cloud, Crystal

 

[kenny]

I'd pick A for the higher color and clarity and it is likely a better-cut diamond than B
I realize HCA is billed as a rejection tool and people usually only use the number score, and the angles input are averages of 8 angles each . . . but I won't apologize for paying attention to all data available to me.
A gets more Excellent marks on the HCA's four categories, and the X falls closer to the AGS 0 region than B does.
HCA says A will have better fire and Scintillation than B.

Also B is kind of deep.

The first one is A.

 

[dicxz80]

I'd pick A for the higher color and clarity.
I realize HCA is billed as a rejection tool and people usually only use the number score, and the angles input are averages of 8 angles each . . . but I won't apologize for paying attention to all data available to me.
A gets more Excellent marks on the HCA's four categories, and the X falls closer to the AGS 0 region than B does.
B is kind of deep.

A get more excellent marks when you use GIA report stats, but not when you are using Sarin report stats, I am also puzzled with the difference

B get about the same HCA score when you are using either GIA / Sarin report stats

can you help to explain about "B is kind of deep" (sorry newbie here)

what will "deep" affect ?

thank you

 

[kenny]

I'd pick A for the higher color and clarity.
I realize HCA is billed as a rejection tool and people usually only use the number score, and the angles input are averages of 8 angles each . . . but I won't apologize for paying attention to all data available to me.
A gets more Excellent marks on the HCA's four categories, and the X falls closer to the AGS 0 region than B does.
B is kind of deep.

A get more excellent marks when you use GIA report stats, but not when you are using Sarin report stats, I am also puzzled with the difference
B get about the same HCA score when you are using either GIA / Sarin report stats
can you help to explain about "B is kind of deep" (sorry newbie here)
what will "deep" affect ?
thank you

No measurement instrument is accurate out to a zillion digits.
Unfortunately all data presented to us reports perhaps one too many significant figures.

I worked in engineering for a couple decades, and we would view this as engineering sloppiness and irresponsible to our clients.
We used Hewlett Packard measuring instruments that sometimes cost hundreds of thousands of dollars, regularly calibrated to traceable standards.
STILL, the rule of thumb is to throw away or round out the last digit the instrument reports.
For instance if a Vector Network Analyzer tells you the gain is 2.247 dB we would either simply ignore and not record that last 7, and report 2.24 dB or round up the number to 2.25 dB.
A good practice is to simply NOT believe the accuracy of last number and measuring instrument gives you.
If the instrument gives you 4 figures, report only 3.

For instance let's say a $3,000 weight scale can accurately measure the weight of a diamond to five places after the decimal point.
Let's say using this expensive scale we could fully believe a diamond truly weighs 1.12345 carat.
(And if we shipped the diamond to the National Bureau of Standards were they have a scale that can measure to, say, 15 digits after the decimal place they would verify that our 1.12345 is correct.)
A $1,000 scale may measure report only four digits after the decimal place (though those four digits would also prove to be accurate) such as 1.1234 ct.

The business with the more expensive scale can round up the five at the end of 1.12345, and report the weight to be 1.1235 (notice they are reporting one less digit) whereas the business using the cheaper scale, if honest, must report the weight as 1.1234.

Such is the quagmire of measurement variations using different instruments, and I suspect that is why we to not see precise repeatability in all the data we are presented with.
It can get to the point of splitting hairs and wondering which data to trust and IMHO the HCA and Idealscope data is enough to make a decision here.

About the depth... there are ranges for depths and 62.5 is on the deep side for a round, even though this particular one has been well cut by having crown angles, pavilion angles and table % to get the diamond to perform quite will in spite of having a 62.5% depth.

All things considered I go with A.

 

[dicxz80]

About the depth... there are ranges for depths and 62.5 is on the deep side for a round, even though this particular one has been well cut by having crown angles, pavilion angles and table % to get the diamond to perform quite will in spite of having a 62.5% depth.

All things considered I go with A.

thank you for your explanation.

indeed A seems better, I am just a bit worried with the "steep" different in HCA score when you use GIA and Sarin report for diamond A

somehow I tend to trust Sarin report as the number is less rounded

any comment on the Idealscope image between diamond A and B ? and any idea why diamond B idealscope looks more "pale"

is it reflecting the diamond B condition compare to diamond A ?

or just merely picture colour enhancement / contrast difference ? or the way they took the picture ?

thank you

 

[kenny]

About the depth... there are ranges for depths and 62.5 is on the deep side for a round, even though this particular one has been well cut by having crown angles, pavilion angles and table % to get the diamond to perform quite will in spite of having a 62.5% depth.

All things considered I go with A.

thank you for your explanation.

indeed A seems better, I am just a bit worried with the "steep" different in HCA score when you use GIA and Sarin report for diamond A

somehow I tend to trust Sarin report as the number is less rounded

any comment on the Idealscope image between diamond A and B ? and any idea why diamond B idealscope looks more "pale"

is it reflecting the diamond B condition compare to diamond A ?

or just merely picture colour enhancement / contrast difference ? or the way they took the picture ?

thank you

Less rounded?

Let's talk about rounding.
There are two kinds of rounding...
1) 1.15 can be rounded up to 1.2 and 1.14 can be rounded down to 1.1.
2) Then there is averaging together several numbers. This is not really rounding but I've noticed rounding is the term used on PS for this. A standard round diamond has 8 "sides". When the HCA asks for THE crown or a pavilion angle (it doesn't ask for all you enter ONE angle, which is an average of all 8 angles.
Both Sarin and GIA must average together 8 angles and report one average of the 8.

Your Sarin report is nice in that it does report the lowest and highest of the 8 angles. (GIA does not reveal this.)
The less the 8 angles vary the more tightly the cutter held to the goal, and A is superior in this way too since it's pavilion angles varied by only 0.1 degree while B's varied by 0.4 degree. The crown angles of both diamonds varied by 0.4 degree.)

Keep in mind we are REALLY splitting hairs here and I'm sure the vendors, appraisers and pros are getting a kick out of me following you out to this level of detail.

 

[kenny]

Yes the difference between the GIA and the Sarin numbers is annoying, but I chalk it up to what I posted above.

Here are the numbers side by side with GIA listed first, and Sarin second...

Diamond A

62.0 62.0
55 54.7
34.5 34.8
40.8 41.0

Diamond B

62.5 62.4
55 55.7
34.5 34.4
41.0 41.0

The only place GIA reports one less significant figure is in the Table percentage.
Notice how many numbers do not match.
Again I chalk this up to what I posted above.
But whom to believe? Flip a coin perhaps, though Sarin reporting an additional digit in Table % and also reporting the highest and lowest Crown and Pavilion angles does make me feel they are being more thorough than GIA.

About the two IS images.
A is on the left.



The overall brightness of the image is just related to the photography exposure not the cut quality or light return.
The extra darkness under the table of A makes me now prefer B, since I think a continuous tone of pink is listed in the chart as Excellent. (But I welcome input from our cut pros on this one.)
Refer to the reference chart for interpreting IS images.



I've changed my mind.
I'd buy B.
HCA of B is under 2 using both GIA and Sarin numbers.
The tone of the pink under the table is closer to the rest of the diamond.

IMHO, cut trumps one grade of color and clarity and you'll get a bigger rock.
But really, these two are so close you could flip a coin and either will be gorgeous.

 

[TitanCi]

I think either will be fine.

I didn't know JA ran Sarins for their customers?

 

[dicxz80]

About the depth... there are ranges for depths and 62.5 is on the deep side for a round, even though this particular one has been well cut by having crown angles, pavilion angles and table % to get the diamond to perform quite will in spite of having a 62.5% depth.

All things considered I go with A.

thank you for your explanation.

indeed A seems better, I am just a bit worried with the "steep" different in HCA score when you use GIA and Sarin report for diamond A

somehow I tend to trust Sarin report as the number is less rounded

any comment on the Idealscope image between diamond A and B ? and any idea why diamond B idealscope looks more "pale"

is it reflecting the diamond B condition compare to diamond A ?

or just merely picture colour enhancement / contrast difference ? or the way they took the picture ?

thank you

Less rounded?

Let's talk about rounding.
There are two kinds of rounding...
1) 1.15 can be rounded up to 1.2 and 1.14 can be rounded down to 1.1.
2) Then there is averaging together several numbers. This is not really rounding but I've noticed rounding is the term used on PS for this. A standard round diamond has 8 "sides". When the HCA asks for THE crown or a pavilion angle (it doesn't ask for all you enter ONE angle, which is an average of all 8 angles.
Both Sarin and GIA must average together 8 angles and report one average of the 8.

Your Sarin report is nice in that it does report the lowest and highest of the 8 angles. (GIA does not reveal this.)
The less the 8 angles vary the more tightly the cutter held to the goal, and A is superior in this way too since it's pavilion angles varied by only 0.1 degree while B's varied by 0.4 degree. The crown angles of both diamonds varied by 0.4 degree.)

Keep in mind we are REALLY splitting hairs here and I'm sure the vendors, appraisers and pros are getting a kick out of me following you out to this level of detail.

thank you for pointing the depth issue.

I learn something new.

after my google session for this topic, indeed 62.5% is in the deep side for round brilliant, some website even categorize it to very good only (no longer excellent)

but since GIA report categorize cut as excellent and I can get consistent HCA score based on GIA and Sarin report, I hope I make "responsible" and "good" decision to have less worry about the depth (as it maybe compensated with the pavilion angle and crown angle)

for the HCA score, I run three times for each diamond, based on SARIN report minimum, maximum, and average value for table size, crown angle, pavilion angle) and one times for GIA report

the Sarin report from JamesAllen is actually not so detailed, I've seen other vendor provide value for each facet

 

[dicxz80]

I think either will be fine.

I didn't know JA ran Sarins for their customers?

you can request Sarin report and Idealscope up to 3 (or 5 can't remember) diamonds for James Allen

Bluenile doesn't provide Sarin report and Idealscope when I ask the chat representative

 

[dicxz80]

Yes the difference between the GIA and the Sarin numbers is annoying, but I chalk it up to what I posted above.

Here are the numbers side by side with GIA listed first, and Sarin second...

Diamond A

62.0 62.0
55 54.7
34.5 34.8
40.8 41.0

Diamond B

62.5 62.4
55 55.7
34.5 34.4
41.0 41.0

The only place GIA reports one less significant figure is in the Table percentage.
Notice how many numbers do not match.
Again I chalk this up to what I posted above.
But whom to believe? Flip a coin perhaps, though Sarin reporting an additional digit in Table % and also reporting the highest and lowest Crown and Pavilion angles does make me feel they are being more thorough than GIA.

About the two IS images.
A is on the left.







I've changed my mind.
I'd buy B.
HCA of B is under 2 using both GIA and Sarin numbers.
The tone of the pink under the table is closer to the rest of the diamond.

IMHO, cut trumps one grade of color and clarity and you'll get a bigger rock.
But really, these two are so close you could flip a coin and either will be gorgeous.

for diamond A, Yes the difference between the GIA and the Sarin numbers is annoying, otherwise I will close eye choose diamond A

I ran report for each diamond, 4 times, 1 times using GIA report, 3 times using Sarin report (minimum, maximum, average value) and diamond B is having more consistent score

The overall brightness of the image is just related to the photography exposure not the cut quality or light return.
The extra darkness under the table of A makes me now prefer B, since I think a continuous tone of pink is listed in the chart as Excellent. (But I welcome input from our cut pros on this one.)
Refer to the reference chart for interpreting IS images.

thank you, now I have one less worry, initially I thought idealscope for diamond B looks "pale" because of light return thingy

that is also puzzling me that for both diamond have "darkness" under table but diamond B has less "darkness"

based on the reference chart excellent should not have "darkness" but "lighter"

but I am completely newbie

IMHO, cut trumps one grade of color and clarity and you'll get a bigger rock.
But really, these two are so close you could flip a coin and either will be gorgeous.

indeed true, as per our discussion above, cut wise more or less same, just diamond B have more consistent HCA score

diamond B have less (only) one color level, clarity also have less (only) one level but clarity wise based on the image under magnifier, I see it very clean (from layman perspective)

diamond B is also almost 300 cheaper

thank you for your help !

 

[dicxz80]

two last doubt !

1.any idea about my concern regarding star / upper percentage ratio ?

2.diamond B is having "thicker" girdle (does this affect fire, brilliance, scintillation, and brightness ??) cant get information from the internet (CONS)

though any medium to slightly ticker should be acceptable range, though some prefer thin to medium

 

[kenny]

Let me guess, you are an engineer.

 

[Laila619]

Hi,

I would pick diamond A, based on the following:

1) it was the gemologist's pick and he/she feels it's slightly brighter
2) higher color
3) better HCA score from the numbers on the cert

Sarin scans are not always 100% accurate, so I wouldn't worry about that. You could run a Sarin on another vendor's machine and get a different result.

 

[dicxz80]

Let me guess, you are an engineer.

I am an IT guy

perfectionist IT guy, never can be statisfied :p

 

[dicxz80]

Hi,

I would pick diamond A, based on the following:

1) it was the gemologist's pick and he/she feels it's slightly brighter
2) higher color
3) better HCA score from the numbers on the cert

Sarin scans are not always 100% accurate, so I wouldn't worry about that. You could run a Sarin on another vendor's machine and get a different result.

2.I personally see diamond in local store to compare H-I-J and almost can't see the different when look from the top (table) except when you see from the bottom side (what is the correct term ?)

3.indeed diamond A is better based on GIA

for the same reasons, we can't say GIA is accurate, that is why I am more comfortable to use both GIA and Sarin stats to get the HCA score and see which diamond is having consistent score. in this case Diamond B

if I choose diamond A, there is chance I will get diamond with 1.3 HCA score which is good, or >2 HCA score which is bad

if I choose diamond B, at least on the paper, I will get good diamond <2 HCA score

 

[Laila619]

Hi,

I would pick diamond A, based on the following:

1) it was the gemologist's pick and he/she feels it's slightly brighter
2) higher color
3) better HCA score from the numbers on the cert

Sarin scans are not always 100% accurate, so I wouldn't worry about that. You could run a Sarin on another vendor's machine and get a different result.

2.I personally see diamond in local store to compare H-I-J and almost can't see the different when look from the top (table) except when you see from the bottom side (what is the correct term ?)

3.indeed diamond A is better based on GIA

for the same reasons, we can't say GIA is accurate, that is why I am more comfortable to use both GIA and Sarin stats to get the HCA score and see which diamond is having consistent score. in this case Diamond B

if I choose diamond A, there is chance I will get diamond with 1.3 HCA score which is good, or >2 HCA score which is bad

if I choose diamond B, at least on the paper, I will get good diamond <2 HCA score

Well, I do see your point. Then I guess in that case, it sounds like diamond B is the best choice since you are most comfortable with that one. It's "mind clean" for you.

 

[dicxz80]

Well, I do see your point. Then I guess in that case, it sounds like diamond B is the best choice since you are most comfortable with that one. It's "mind clean" for you.

no choice for me, since it is online buying, can only rely on paper, report and images.

I wish I can see with my own eyes for both diamond

I actually prefer diamond A better colour, better clarity (safer from unwanted inclusion since buying online) but Sarin report for it scare me away from it

 

[dicxz80]

two last doubt !

1.any idea about my concern regarding star / upper percentage ratio ?

2.diamond B is having "thicker" girdle (does this affect fire, brilliance, scintillation, and brightness ??) cant get information from the internet (CONS)

though any medium to slightly ticker should be acceptable range, though some prefer thin to medium

any help on this please ?

 

[Dancing Fire]

based on the #s i like A...

 

[dicxz80]

based on the #s i like A...

what is #s ?

 

[dicxz80]

two last doubt !

1.any idea about my concern regarding star / upper percentage ratio ?

2.diamond B is having "thicker" girdle (does this affect fire, brilliance, scintillation, and brightness ??) cant get information from the internet (CONS)

though any medium to slightly ticker should be acceptable range, though some prefer thin to medium

any help on this please ?

any kind soul can help with this question ?

thank you

 

[dicxz80]

two last doubt !

1.any idea about my concern regarding star / upper percentage ratio ?

2.diamond B is having "thicker" girdle (does this affect fire, brilliance, scintillation, and brightness ??) cant get information from the internet (CONS)

though any medium to slightly ticker should be acceptable range, though some prefer thin to medium

any help on this please ?

any kind soul can help with this question ?

thank you

 

[kenny]

based on the #s i like A...

what is #s ?

# is a symbol for numbers, as in all the data presented.

Girdle thickness of these two diamonds is fine.
The thicker one will not look any more dull or dark because of the thicker girdle.

The thinner the girdle the more susceptible it is to chipping.
The thicker it is the more is just sort of is a wasted weight you are paying for.
Both A and B are fine with Medium to Slightly Thick girdles (3.5%) and (4.0%).

The star facet stuff is over my head, but maybe someone else will respond.

I must add that you are taking this really far.
It is like you are shopping for a car and using a micrometer to measure the thickness of every part of the car and hiring a metallurgist to analyze the alloy of every metal part.

At some point you have to just pick one and drive it off the lot.

 

[dicxz80]

based on the #s i like A...

The thicker one will not look any more dull or dark because of the thicker girdle.

thank you so much ! I am looking for this information

The thinner the girdle the more susceptible it is to chipping.
The thicker it is the more is just sort of is a wasted weight you are paying for.
Both A and B are fine.

again thank you, same as what I read from internet

any idea about the star / upper ratio ?

 

[kenny]

based on the #s i like A...

The thicker one will not look any more dull or dark because of the thicker girdle.

thank you so much ! I am looking for this information

The thinner the girdle the more susceptible it is to chipping.
The thicker it is the more is just sort of is a wasted weight you are paying for.
Both A and B are fine.

again thank you, same as what I read from internet

any idea about the star / upper ratio ?

This link has a section that explains this.
Scroll down to the middle of the page.

http://www.goodoldgold.com/classic.php?page=minor_facets.htm

 

[dicxz80]

based on the #s i like A...

The thicker one will not look any more dull or dark because of the thicker girdle.

thank you so much ! I am looking for this information

The thinner the girdle the more susceptible it is to chipping.
The thicker it is the more is just sort of is a wasted weight you are paying for.
Both A and B are fine.

again thank you, same as what I read from internet

any idea about the star / upper ratio ?

This link has a section that explains this.
Scroll down to the middle of the page.

http://www.goodoldgold.com/classic.php?page=minor_facets.htm

again.. thank you so much for your help

the link is helping me alot to learn not about star ratio also about lower girdle percentage and understand more about idealscope image

 

[dicxz80]

after the last link given by Kenny, I think more or less I've completed to gain enough knowledge as newbie to decide

in the end I need to decide between these 2 diamonds (after sleepless night filtering those diamonds in James Allen)

my conclusion :

• diamond A and B at least don't have feather (crack) inclusion and both clean to my eye under magnifier, with diamond B is cleaner
• diamond A in fact have better idealscope image, see my attachment for the are I mark with green circle, that will produce more scintillation (now I know why JamesAllen representative said diamond A is his preference and diamond A will sparkle better
• diamond A have better HCA score with GIA stats but not consistent with Sarin report, if I have time I may want to ask James Allen to run the Sarin report again or ask for detail Sarin report
• diamond B have more consistent HCA score using GIA stats and Sarin report stats
• diamond A, based on the idealscope image, I suspect have a bit light leakage, in the are below star on the 12o'clock
• diamond B have overall more consistent idealscope image (see the circle green mark in right image), despite of diamond A have better idealscope image (I can't explain in better term) see point 2,

note : for the attachment, diamond A is on the left, diamond B is on the right

my rant and comment :

• generally I am happy with these two and can't even decide until now, but have to decide between these two, I wish I have more time to search better diamond
  
  bigger lower gridle % (more sparkle and more intense) but not those extreme 85%
  bigger star ratio
  bigger table %
  less total depth %
  better hca score
  
  
• but at least now I have better general knowledge of diamond (1-2 months back I know nothing) that will be helpful if in future I want (and will) buy bigger diamond to appreciate my wife to be more
• this diamonds may good on the paper, but I think if you can go to the store and see it with your own eyes, it will be much better
• as per the online sellers that I visited
  
  JamesAllen has good number of stocks, and has enough information for newbie like me to choose diamond (Sarin report and idealscope image, need to request and require 3-5 days) and generally cheaper and free shipping internationally
  
  Bluenile has good number of stocks, but no Sarin report, no idealscope (big no for me)
  
  whiteflash, goodoldgold, briangavindiamond, they have less stock of diamonds, but I think their diamonds are "pre-selected" diamonds, have a good specs, pricewise is generally 10-20% higher compare to JamesAllen (same spec)
  
  I specially like goodoldgold, as they put all detailed information that you want for their diamonds, e.g. : ASET, idealscope, detail Sarin report (all ready to use ! you can select and decide faster)

last but not least, I want to say thank you for everyone who helped me (especially kenny) and truthaboutdiamond (Mike) who also helped me (through email)

I will update this thread later on with picture, once I receive the diamond

and I may also need help to select with ring setting selection

 

[kenny]

Isn't Pricescope wonderful!!!???