visible difference between F & G colours?

[Mara]

Daniela--Exactly...just as if a stone is H&A does not necessarily mean hands down that its a no brainer great stone.




No H&A doesn't mean bad stone...and H&A doesn't mean absolutely great stone. There is more to it than just the H&A

 

[AGBF]

Earlier in this thread Marty Haske wrote:

"See figure 8 on http://www.gis.net/~adamas/sas2000.html which addresses the 1942 MacAdam study on human color vision color discrimination ability around the reference white position on the CIE chromaticity diagram... The MacAdams study is still in current Color Science texts like "Color Science, Concepts and Methods,, Quantitative Data and Formulas" by Wyszecki and Stiles... "

This is the chart which is pictured at the location he mentions on his website. About it he writes:

"The SAS2000 uses multiple color difference formulations to estimate diamond color grade. One of the problems in diamond color grading is that the separations in color space of diamond color grades are VERY compressed in the colorless to near colorless range. Figure 8 shows the chromaticity coordinates of the SAS2000 diamond masters, from E to O. Superimposed on this plot are the closest one sigma and three sigma MacAdam uncertainty ellipses. The MacAdam ellipses are one of color sciences reference points, empirically derived through testing, estimating human repeatability in color matching, which is the essence of diamond color grading. The color science texts state that the "just noticeable difference was found to be about three times as large as the corresponding standard deviation", sometimes called the Discrimination Ellipse. In lay terms approximately 68% of the time, the human observer's color matching will fall within the 1 sigma ellipse. As can be readily seen, the one sigma ellipse incorporates more than two color grades in the colorless to near colorless range. Of particular interest is that the 1 sigma MacAdam ellipse shown is both the closest, centered at [.305, .323 ] on the chromaticity diagram, and the smallest of the 25 ellipses within the CIE diagram. We should note also the 58 degree orientation of the ellipse, which corresponds almost exactly to the "hue angle" of the cape series masters. Perhaps this is one of the reasons one finds so much discrepancy or variation with human color grading."

 

[AGBF]

These were Toska's original comments:

"I am tossing up between a F colour of G colour diamond.

If an ideal cut F coloured diamond is held next to a G colour diamond, is the colour visibly noticeable? I don't know if its worth paying the extra money for a 'clear' colour diamond."

Getting back to the original question of F versus G I would say that Marty's chart would indicate that the human eye doesn't perceive a difference between an F and a G. I am sure that is too simplistic, but it appears to me to be the bottom line.

What do you engineers say?

 

[magna2]

----------------
On 11/6/2003 8:59:46 PM AGBF wrote:

These were Toska's original comments:

'I am tossing up between a F colour of G colour diamond.

If an ideal cut F coloured diamond is held next to a G colour diamond, is the colour visibly noticeable? I don't know if its worth paying the extra money for a 'clear' colour diamond.'

Getting back to the original question of F versus G I would say that Marty's chart would indicate that the human eye doesn't perceive a difference between an F and a G. I am sure that is too simplistic, but it appears to me to be the bottom line.

What do you engineers say?

----------------

Unfortunately, Marty's engineering degree is from MIT whereas my came from Western New England College, so even in Marty's layman terms I am not quite sure exactly what he stated. If I read and interpret correctly, the chart shows that 68% of the time a person looking at the various E to G color diamonds will not be able to discern an E from a G since it falls within 1 sigma of the chromaticity and that it is indistinguishable to discern between a F and a G.

Conclusion - save your hard earn money because chances are that no one is going to be able to tell the difference between the two colors (F & G).

 

[elmo]

----------------
On 11/6/2003 8:59:46 PM AGBF wrote:

Getting back to the original question of F versus G I would say that Marty's chart would indicate that the human eye doesn't perceive a difference between an F and a G. I am sure that is too simplistic, but it appears to me to be the bottom line.

What do you engineers say?

----------------

Thanks for getting us back to the original question, AGBF

. I can fairly easily see a subtle but visible difference in "warmth" between one friend's GIA graded AGS-ideal G and another friends GIA-graded AGS-ideal F, no fluorescnce in either. Both stones are close in size, in the 3/4 carat range. Maybe the F is closer to an E, and the G is closer to an H? The G is actually a slightly better looking stone. So in response to the original question, if they both look like good candidates I'd look at both diamonds and look at how they're priced. Funny how people decide "this is the one" from just looking at a piece of paper.

 

[Toska]

Thank you AGBF and everyone else. It's definately going to be a G diamond. At first, I wanted an 'E' just for the simple fact that it looks good on paper when it says "colourless" She will get the ring, look at the paper and probably lock it away somewhere never to look at it again. When it comes down to it, I want her to be able to say she has a 1 carat stone and a great cut.

I'm finding it toough to find good diamonds. Just when I think I have made the right decision, the stone is sold!

I will keep looking and post my latest choices for scrutinizing, by all the pricescope pros.

 

[canadiangrrl]

Sounds like you're on the right track.

The holiday season is a busy time of year for jewlery vendors, so there may be more than one stone you're interested in that gets sold from under your feet, unfortunately. Don't know what your timelines are on the engagement, but if you want to do something around Christmas, there's no time like the present. But hey, no pressure.

 

[Toska]

I am going on a holiday at Christmas, I need for then

The pressure is on, I have about one month to find one!

 

[hoorray]

Hi Toska,

A quick search at www.usacerteddiamonds.com brings up 2 Surpurbcert diamonds that look pretty great. They have lots of reports with them that you might want to check out too.
1. 2055 Round 0.92 F VS2 $5,175.92
http://www.superbcert.com/Information/off_site_diamond_search.cfm?Action=View_Diamond&Product_Group_ID=1&Product_Category_ID=3&Product_ID=820

2. 2056 Round 0.95 G VS2 $5,225.00
http://www.superbcert.com/Information/off_site_diamond_search.cfm?Action=View_Diamond&Product_Group_ID=1&Product_Category_ID=3&Product_ID=821

good luck in your search!

 

[AGBF]

Thes beast of luck, Toska! Do stay in touch during your search!

 

[Toska]

How does this diamond shape up? What are the pro's and con's of this diamond?


Certification: DCLA (Diamond Certification Laboratory of Australia)
Size: 1.02 ct
Color: G
Clarity: SI1
Measurements: 6.54 - 6.57 x 3.88
Roundness: 0.5%
Total Depth: 59.2%
Table Size: 59.7%
Crown Angle: 33.5
Pavilion Angle:40.7
Culet: 0.8%
Polish: Excellent
Symmetry: Excellent
HCA 1.4 within (TIC)
Inclusions: Semi Scattered colorless crystals
Black inclusions: None

Price: AU$7592 including GST tax or US$5384 including GST tax.

For people who live in the U.S and wouldn't have to pay GST tax the diamond is selling at $4762US

 

[fire&ice]

from the specs - looks very nice.

However, I am unfamiliar w/ the lab as I reside in the states.

 

[mdx]

Hi Fire&Ice

In case you are interested in DCLA
.
The DCLA is an internationally recognised Laboratory, grading to International Diamond Council (IDC) rules, established jointly by the World Federation Of Diamond Bourses (WFDB) and the International Diamond Manufacturers Association (IDMA).
They are the only Australian laboratory endorsed by the Jewellers Association of Australia. HRD are also grading to IDC rules

http://www.dcla.com.au

Regards
Wayne
Melbourne Diamond Exchange Ltd