Does colour grade affect light return/performance

[BobR]

My wife has a pair of 3 stone studs (0.27ct each stone) all GIA graded FSI1. The proportions vary; with table varying from 55 - 61% and 4 of the 6 qualify as GIA Ex/AGS Ideal base on proportions with the other 2 rating GIA/AGS VG.
We have just bought a 3 stone pendant all GIA/AGS GSI1
The centre stone is GIA triple x 0.8ct (57t/34.5ca/41pa) The 2 side stones are 0.31 AGS(0) (56t/34ca/40.9pa) branded H&A.

Now we are very happy indeed with both items of jewellery BUT (to our untrained eyes) the intensity of light return from the F colour studs seems marginally greater than the G clour pendant ( in all artific1al lighting and also direct sunlight). (although we believe the pendant stones have more ''character and beauty'')

Could this be as a result of the colour grade, or is it purely coincidental (or indeed just our untrained eyes)?? (both settings are claws and with open backs)

As an aside and relating to the ability to distinguish between colur grades, my wife, having had the f colour earrings for a while, was immediately able to correctly guess the colur grade of pendant, so some people can discern colour differences of 1 grade even when mounted.g

 

[oldminer]

The human eye cannot distinguish the lesser light return of an F color which is identically cut, and totally equal in all other respects to a G color. The fact that a G color is absorbing more light than an F color is a scientific truth, but invisible. The reason your other half sees a visible difference between F and G stones is the way each is cut. The darker color is fashioned in a way which makes its color more eye apparent. The difference would be invisilbe in the face up direction if the stones were all totally identically cut.

 

[BobR]

Date: 1/18/2010 1:24:02 PM
Author: oldminer
The human eye cannot distinguish the lesser light return of an F color which is identically cut, and totally equal in all other respects to a G color. The fact that a G color is absorbing more light than an F color is a scientific truth, but invisible. The reason your other half sees a visible difference between F and G stones is the way each is cut. The darker color is fashioned in a way which makes its color more eye apparent. The difference would be invisilbe in the face up direction if the stones were all totally identically cut.

Thanks David
1) In red - I assume a typo - you meant lesser lght return of G colour??
2) If it''s the cut that''s giving me the difference then that means we are (or so we believe) getting better light return from the earring stones which, although well cut, are further away from the preferred range as I understand it of:-
table - 55-57
CA - 34-35
PA - 40.6 - 41

 

[stone-cold11]

so what is the number for the studs?

 

[BobR]

Studs are
1) t 60 ca 32 pa 41.2
2) t 55 ca 32.5 pa 41.4
3) t 61 ca 33.5 pa 40.6
4) t 61 ca 36.5 pa 40.8
5) t 58 ca 33.5 pa 41
6) t 55 ca 33.5 pa 41



As I said the tighter cut G colour pendant stones definitely have more character and we believe perform better in diffused daylight. In direct sunlight stones 1 and 2 in the studs produce the most intense flashes.

 

[stone-cold11]

studs 1, 2 are more cut for brilliance, if the pav angles are slightly lower, they would be what is termed BIC here.

Also depends on the lower girdle facets size.

The preferred range is TIC which is cut for a balance of brilliance and fire return. Regarding colors, difficult to tell if your wife is very sensitive to color or just a lucky guess, maybe get her a set of almost the same measurement studs of E/H and mix them up for her to guess again?

 

[BobR]

The lgfs on studs 1-3 are 85, on 4-6 are 80, whereas they are 75-80 on pendant.
Yeah I guess it''s worth looking at B&M and getting them to pull a couple of similar rings with a grade or 2 colour diff and see if she can identify. But looks like I''ll be sticking with F in the future!!
Interestingly for me, whilst I can''t see any colour in g or f (mounted) , the f stones in earrings do appear whiter (in diffuse daylight) than the g pendant.

 

[MichelleCarmen]

Hi,
My G has a bit more warmth than my E and F stones. It''s always possible that the G you have is more toward an G/H than an F/G. I''ve always wondered if my G GIA cert stone is more like an H.

 

[Lekde]

My K colored e-ring outshines my E-F colored studs. However, my e-ring is a OMC and one of my studs is an OEC. Under the same types of light, my K colored OMC oushines my E-F OEC.

I don''t know if that helps considering it''s not a technical response, but from what I can tell, the K color doesn''t affect the light return.

 

[BobR]

Yeah
I''ll be getting pendant appraised for UK insurance soon. Interesing to see what colour the appraiser comes up with (especially if it''s the same person who did the GIA graded f earrings, which she said were e/f.

 

[oldminer]

Less light from a G versus F is a good correction. Sorry for any confusion.

 

[Rockdiamond]

Date: 1/19/2010 4:45:16 AM
Author: BobR

Date: 1/18/2010 1:24:02 PM
snip.... the preferred range as I understand it of:-

table - 55-57

CA - 34-35

PA - 40.6 - 41

HI Bob, by no means is this "preferred range" agreed upon by diamond professionals.
It''s the preferred range here on PS, but not in the industry at large.

If judging diamonds was done on an absolute basis of "light return" and "performance" as they are judged here on PS there would be no reason to cut anything other than colorless rounds.

As an example, consider Fancy Colors- which can cost more than colorless stones- and in some circles are considered more desirable.
Judged on a strictly "light return" basis, they could be considered "defective"

 

[yssie]

2) If it's the cut that's giving me the difference then that means we are (or so we believe) getting better light return from the earring stones which, although well cut, are further away from the preferred range as I understand it of:-
table - 55-57
CA - 34-35
PA - 40.6 - 41

Nice guidelines, not gospel - can have excellently cut stones outside these ranges. Getting further from the preferred range is (up to a point, obviously) a matter of preference - noone can say that a well cut 33/41 performs better or worse than a 36/40.6, just differently, and one will appeal more to some than the other, and still others would choose neither and go for a more balanced stone..


If you prefer the intensity of white light return from the studs (that's the way those combos lean) then you now know that's something to look for in future purchases. I would wager that this, rather than the fact that the pendant is a G, is the difference that you're seeing between the two.