How to tell light performance with naked eye

[Beyar90]

I recently purchased this centre diamond https://www.jamesallen.com/loose-di...i-color-vs1-clarity-excellent-cut-sku-3185709 for this setting https://www.jamesallen.com/engageme...ment-ring-with-scroll-undergallery-item-41658). I think it looks fantastic (but what do I know, I have nothing to compare it to)

For comparison's sake, I also purchased this ring from Costco with the intent to return it (but the yellow gold version) https://www.costco.ca/Three-Stone-R...Wedding-Set-(1.00-ctw).product.100107204.html

Since the Costco one does not come with a GIA report or a cut grading, I was expecting the JA ring to blow the Costco one out of the water as far as visible light performance; however, to be honest, the Costco diamond actually seems to be very slightly more brilliant (from my untrained eye).

I am wondering if this is due to the following possible reasons:
-The Costco ring having slightly larger stones (flashes of light from the facets are simply more noticeable and not necessarily more brilliant?)
-The Costco ring by fluke actually has a better cut stone, (or the JA stone, despite having good proportions and HCA score of 1.0, is a weaker performer based on other diamond aspects)
-The JA setting is inhibiting some of the light return (the prongs on the JA stone are larger in diameter, therefore taking up more real estate on the diamond).
Or maybe I just suck at determining the intricacies of light performance with my naked eye.

I will post some pictures/videos, but do you have any suggestions for lighting conditions/patterns of movement to compare the rings under where the differences in cut would really be noticeable? Since cut is king, I was expecting the differences to be night and day. But to me, I barely notice a difference between the two rings.

Thanks,

Ben

 

[flyingpig]

For light return, you want even diffused lighting.
https://www.pricescope.com/communit...ance-diamond-photography.227610/#post-4108627

For fire, sparkle, and scintillation, you want multiple spot lighting, which is harder to create at home and capture with a camera. This is very tricky..
See strong light from multiple light sources. This is why diamonds sparkles more in a jewelry case or store.
http://www.logisticsled.com/UserFiles/logistics-1.jpg
http://diamondswest.com/wp-content/uploads/2015/01/Jewelry.Store_.jpg

The best spot to observe fire and sparkle is inside an elevator, if the lighting looks like this.
https://www.forms-surfaces.com/site...l-reg-2x/images/6.1_16M_4323_11292011_0_0.jpg

I also like assess diamonds under daylight (no direct sunlight). You can do this outdoor, or indoor with diamonds facing the window.

 

[LLJsmom]

Unless super obvious, different settings can have a huge impact on how a diamond performs.

We need to see pictures.

 

[drk14]

How much have you handled the rings? A little bit of skin oil (e.g., fingerprint) can go a long way towards extinguishing the brilliance of a diamond. Make sure the diamonds are clean before evaluating.

Also, when you say you are comparing how "brilliant" the two diamonds are, what are you looking for? Overall brightness of the reflected light is not a sufficient criterion. You need to tilt the diamonds slowly back and forth, and observe whether you see flashes that turn on and off, originating from the facets of the diamond.

Finally, do you have any IdealScope or ASET images of your GIA diamond? Just because it scores HCA=1.0 doesn't guarantee that it will have excellent light performance.

 

[Beyar90]

For light return, you want even diffused lighting.
https://www.pricescope.com/communit...ance-diamond-photography.227610/#post-4108627

For fire, sparkle, and scintillation, you want multiple spot lighting, which is harder to create at home and capture with a camera. This is very tricky..
See strong light from multiple light sources. This is why diamonds sparkles more in a jewelry case or store.
http://www.logisticsled.com/UserFiles/logistics-1.jpg
http://diamondswest.com/wp-content/uploads/2015/01/Jewelry.Store_.jpg

The best spot to observe fire and sparkle is inside an elevator, if the lighting looks like this.
https://www.forms-surfaces.com/site...l-reg-2x/images/6.1_16M_4323_11292011_0_0.jpg

I also like assess diamonds under daylight (no direct sunlight). You can do this outdoor, or indoor with diamonds facing the window.

Thanks for these tips, I will try this at when I get home!

How much have you handled the rings? A little bit of skin oil (e.g., fingerprint) can go a long way towards extinguishing the brilliance of a diamond. Make sure the diamonds are clean before evaluating.

Also, when you say you are comparing how "brilliant" the two diamonds are, what are you looking for? Overall brightness of the reflected light is not a sufficient criterion. You need to tilt the diamonds slowly back and forth, and observe whether you see flashes that turn on and off, originating from the facets of the diamond.

Finally, do you have any IdealScope or ASET images of your GIA diamond? Just because it scores HCA=1.0 doesn't guarantee that it will have excellent light performance.

Both rings have not been handled much, and I avoid touching the stones as much as possible. As far as what I'm looking for, I mean the overall sparkle factor which you mentioned, the eye-catching ability of the facets turning on and off when I rock the ring back and forth slowly. Also, I hear yah regarding the ASET/idealscope images. I really should have asked before I purchased the diamond. Do you think it would be worth it to take both rings to an appraiser and request these images? What I really wish is access to a ring with a known ideal stone and compare it to what I've got because I really don't have a reference point.

 

[WinkHPD]

You can contact David Atlas (Old Miner here) and for not very much purchase both an Ideal-scope and an ASET. With these you can look at the diamonds and decide which has the best light return. You can also look at videos on Garry Holloway's site, https://ideal-scope.com/how-to-use-ideal-scope-products/.

They are a very helpful set of tools to use when looking at diamonds in real life rather than on paper.

Wink

 

[OoohShiny]

Hold the rings underneath a table, so there is no direct light hitting them - a well-cut stone should remain pretty (surprisingly!) bright across the stone, from edge to edge. A poorer cut stone will look dark, as I understand it.

 

[Karl_K]

The biggest thing is look at them under as many lighting conditions as possible making sure both are clean.
Returning light and looking good in many lighting conditions is the goal of a well cut stone not being the brightest in one lighting condition.
As far as sparkle sometimes a less well cut stone can have more flashes in some lighting but look not as well in many others.
Everything is a trade off when it comes to diamond cut/design.

 

[Karl_K]

For example:
Candle light
A well cut oec or asscher or emerald will blow any mrb away by a far margin.
Yet the well cut RB has enough larger and med virtual facets not to look dead and actually look pretty good.