Do ideal cut diamonds appear darker than vg cut??

[diamondgezer]

My wife has a pair of earrings set with f color rb diamonds and a pendant set with g color rb diamonds. Both are set in 18k white gold.

The g color (ideal cut) stones appear 'darker' to us (or maybe better to say not as white, but not really more tinted) than the f color (vg cut) in most lighting conditions. This has intrigued us for some time. We bought both pieces of jewelry (and diamonds) from (different) online vendors. I have read many comments that the difference between f and g is not discernible to the untrained eye when face up, let alone when set.

This is not about the performance of the stones - although we're happy with the earrings. we're ecstatic with the pendant.

My wife will be having a BIG birthday in a year or so and I would like to buy her a solitaire. I was thinking of dropping color to an h to maximize size for budget.

My concern is that what we're seeing with the g stones is in fact the difference between f and g color, in which case dropping to an h is likely a no no!!

I know the easiest way to check is to go and see some f/g/h diamonds in person, but that would alert her to my plans.

So I'm looking for opinions as to what, if anything else could be causing this affect.

1) Do ideal cut stones by character appear darker than vg? (more contrast??)

2) Could the natural tone of the diamond material cause this. (Coincidence as all 3 stones are darker)

3) Could it be the settings which to my uneducated eyes look the same, 4 prong settings for both pieces, exposed sides, and an opening in the setting at the base of each stone??

4) Is it related to size of stones

5) Any other possible cause

Some details - the 6 f color earring stones are GIA certed F/SI1 with a mix of 1 good/ 4 very good and 1 excellent cut each weighing between 0.26 and 0.29 ct

the 3 G color pendant stones are GIA/AGS certed G/SI1 all triple X, 2 (H &A) weigh 0.32 ct each and the centre weighs 0.8 ct

If the opinion is that what we're seeing is NOT the color difference between f and g then are we safe going to h? ( and are we then risking seeing color difference between f and h?)

If anyone can shed light (no pun intended!!) on the above I'd be really grateful.

 

[luvdajules]

I'm a newbie too, but my guess is that it's the setting somehow and possibly the larger size of the pendant center stone, so a perceived darker look. Some people might focus on the gradings (each cut grade/color/clarity grades all have ranges) or who did the gradings. But it's probably a simpler answer. Pics might help regarding opinions of the settings. I'm also assuming you're making these observations in hand (both perfectly clean), scrutinizing them, not in her ears and around her neck. For clarification, why are you estatic about the perceived darker pendant, I didn't follow that.

But to answer your real question, I would think going to an H color would still be very white, just stay with the GIA XXX cut stones or AGS0. There's many helpful experienced members who could help you find some great options in your budget if you'd care to share more of what you were thinking for the ring.

 

[diamondgezer]

Hi Luvdajules
Yes I'm talking about scrutinizing close up not wearing them.
I was trying to say that the perceived darker stone is an integral/background feature of the stone color or hue and has no bearing on the scintillation or fire. In terms of brightness there is more contrast in the ideal g stones and I'm questioning whether this contrast is contributing to our perception of a different shade.
I'll try and get some photos of the settings uploaded later
thanks for the comment

 

[yssie]

My wife has a pair of earrings set with f color rb diamonds and a pendant set with g color rb diamonds. Both are set in 18k white gold.

The g color (ideal cut) stones appear 'darker' to us (or maybe better to say not as white, but not really more tinted) than the f color (vg cut) in most lighting conditions. This has intrigued us for some time. We bought both pieces of jewelry (and diamonds) from (different) online vendors. I have read many comments that the difference between f and g is not discernible to the untrained eye when face up, let alone when set.

This is not about the performance of the stones - although we're happy with the earrings. we're ecstatic with the pendant.

My wife will be having a BIG birthday in a year or so and I would like to buy her a solitaire. I was thinking of dropping color to an h to maximize size for budget.

My concern is that what we're seeing with the g stones is in fact the difference between f and g color, in which case dropping to an h is likely a no no!!

I know the easiest way to check is to go and see some f/g/h diamonds in person, but that would alert her to my plans.

So I'm looking for opinions as to what, if anything else could be causing this affect.

1) Do ideal cut stones by character appear darker than vg? (more contrast??)
Yes, of a sort. Quantity and quality of light return can make a diamond look "darker" in intense lighting conditions like sunlight.
[URL='https://www.pricescope.com/community/threads/why-does-my-diamond-go-dark-in-the-middle.156211/']https://www.pricescope.com/community/threads/why-does-my-diamond-go-dark-in-the-middle.156211/[/URL]

2) Could the natural tone of the diamond material cause this. (Coincidence as all 3 stones are darker)

3) Could it be the settings which to my uneducated eyes look the same, 4 prong settings for both pieces, exposed sides, and an opening in the setting at the base of each stone??

4) Is it related to size of stones
Yes, of a sort. Larger stones return light differently - this affects face-up appearance.
[URL='https://www.pricescope.com/community/threads/high-contrast-in-ideal-cut-diamonds-and-effect-on-appearance.144474/']https://www.pricescope.com/community/threads/high-contrast-in-ideal-cut-diamonds-and-effect-on-appearance.144474/[/URL]


5) Any other possible cause

Some details - the 6 f color earring stones are GIA certed F/SI1 with a mix of 1 good/ 4 very good and 1 excellent cut each weighing between 0.26 and 0.29 ct

the 3 G color pendant stones are GIA/AGS certed G/SI1 all triple X, 2 (H &A) weigh 0.32 ct each and the centre weighs 0.8 ct

If the opinion is that what we're seeing is NOT the color difference between f and g then are we safe going to h? ( and are we then risking seeing color difference between f and h?)
IMO the effects you're describing are very unlikely to be due to the body colour grade difference.

If anyone can shed light (no pun intended!!) on the above I'd be really grateful.

 

[John P]

More threads if you're interested:

Darkness in Ideal-Cut diamonds revisited
https://www.pricescope.com/community/threads/darkness-in-ideal-cut-diamonds-revisited.150108/

Diamond sparkles more in dim light
https://www.pricescope.com/community/threads/my-diamond-seems-to-sparkle-more-in-dim-light.122718/

 

[luvdajules]

Thanks, John for linking these threads. I have so much more to learn about diamonds . So very informative and interesting.

 

[diamondgezer]

Thanks Yssie and John

I need to find some time to digest the details in those links but on skimming I feel reassured that it's unlikely to be the difference in colour.

Yssie - Can you expand on one point - you say ''Larger stones return light differently' I'm a novice in this area but at first off this seems odd! Two 2 rb diamonds of the same angles and proportions must be similar in a mathematical sense?? So I would expect white light to be reflected around the diamond in an identical manner irrespective of the size?? Are you referring to dispersed lighting (fire)?

Please explain what is probably an oversimplification on my part. (or maybe there's already a topic that explains this??)

 

[diamondgezer]

Yssie

Just read the link you pointed to, in some more detail. My point is certainly an oversimplification.

But still intuitively I have the same question (I've not considered refraction here). Relating to the link - why do larger (but mathematically similar) facets cause difference in light return??

Please humour this complete beginner as far as diamond optics are concerned.

 

[yssie]

It's because of the way our eyes see things - the limits of our visual perception and acuity.

Say, like you suggest, you've got two diamonds - a 2ct and a 0.2ct. The only difference between them is one of scale - they're the same body colour (eliminating absorption differences), FL clarity (no inclusions appreciably affecting light return), and they've exactly the same proportions all around the stone, it's just that the facets on one are a lot bigger than the facets on the other.

Both diamonds are cut into 57 flat physical facets. When you look into the stone you see dozens and dozens of other smaller facets though, these are "virtual facets". They behave just like "real" facets would - they can do one of three things at any point in time: return light, obstruct (turn dark because they're reflecting something dark), or leak (allow light to escape). Karl wrote an article for PS about virtual facets in step cuts, it's a really good intro to the idea:
http://www.pricescope.com/journal/virtual-facets-and-patterns-discussion-about-step-cuts


http://agslab.com/spie/spie_lo_res.pdf

A number of PSers have noted that smaller stones tend to *twinkle* quickly whereas larger stones throw out fewer slower big bold flashes of light - this is because larger facets have the potential to output higher-energy refractions to your eyes than smaller facets do. Larger virtual facets allow higher-energy inbound refractions, and assuming the stones are spotlessly clean and identically proportioned the energy loss by percent is the same so the outbound refractions that you see are also higher-energy. Higher-energy refractions = bigger, bolder flashes of light, which our eyes interpret as "brighter" and "whiter", and focusing on a single high-energy outbound refraction makes the rest of the stone go "dark" by comparsion - so what you're really seeing is a localised example of the 'why does my stone go dark in sunlight' links! These flashes look slower because our eyes are actually able to resolve them individually, but we automatically focus on the brightest, one at a time. You see more colour because the outbound refractions are actually always dispersions, which when larger and higher-energy allows your pupils to actually isolate and focus on one component wavelength.

 

[John P]

Yssie covered the basics well, and the linked article on step-cuts is informative.

Virtual facets are defined as the appearance of smaller facets within larger facets, in the form of surfaces or images, which occur due to reflection and refraction within a diamond. Logically, the larger the virtual facets the better chance your eye will detect the optical event occurring - whether reflection, refraction, shadow/obstruction or leakage/windowing.

Refraction (light dispersed into its spectral colors) is especially critical: In order for your eye to detect color, your pupil must 'clip' the dispersed fan, rather than seeing the entire fan - because when recombined it's white light.

There are illustrations here, showing the pupil clipping light based on less physiological dilation.
https://www.pricescope.com/communit...re-in-dim-light.122718/#post-2144375#p2144375


Larger fans of dispersion have a better chance of being seen as color rather than white light.
Larger reflections have a better chance of being seen (as opposed to being small/weak and invisible).
Larger obstruction events create more dynamic contrast with the bright areas around them.

Thus, in general, the larger the diamond the larger the virtual facets. It's why extra-faceted cuts look better (to me, others may have different taste) in 3ct+ sizes when in normal lighting. The more-abundant VF events have a better chance to be seen at an increased size.

Additionally, the higher the order of 3D cut precision the larger the virtual facets. Since virtual facets are reflections, their size and quantity vary depending on how precisely the diamond was cut in all three dimensions. A diamond with perfect 3D cut precision would have facet reflections which line up precisely with matching facets on the opposite side, creating overlapping/symmetrical facet reflections with larger surface areas, per the diagrams Yssie posted above.

By contrast, a diamond with asymmetrical cut precision has reflections which don’t line-up with opposite facets, causing broken secondary and tertiary reflections which are much smaller, so less color is seen and many events become weak or invisible. This is what causes a "crushed ice" appearance.

What's fascinating to me is that diamond cutters were aware of these things prior to modern research: Antique rounds from the early 1900s were fashioned with extremely wide pavilion mains, small tables and high crowns. This maximized dispersion by increasing the size of the virtual facets, without the aid of modern tools or modeling. In fact, use of the term "fire" to describe refraction comes from that time. The description was literally about maximizing the reflection/refraction of the fire coming from the gas lamps under which diamond cutters worked in those days.

 

[diamondgezer]

Yssie/John

Many thanks for taking the time to give such a comprehensive response!!

My 'oversimplification' was an 'understatement'

I certainly have homework reading for this Eastertide!!

 

[TC1987]

Not sure if one of those linked articles mentioned FIC, "firey ideal cut." [URL='https://www.pricescope.com/community/threads/fic-proportions.9305/']https://www.pricescope.com/community/threads/fic-proportions.9305/[/URL]
Taller crown, steeper crown angle, small table, shallower pavilion angle, deeper ( >61% up to 65% depth) -- Returns more fire, returns less brilliance (white light), and can look "dark" at times.