How do I find LGD with Gemex reports?

[finalgears]

Hi, anyone know any LGD diamond vendors that offers GIA and GEMEX reports on their diamonds? I've been looking at Brilliant Earth LGDs as they have the largest selection, good prices, but they don't offer the GEMEX, which I'm hoping to help rate the light performance.

I want a diamond that is the best cut, green HCA score, and high GEMEX scores

 

[Sprinkles&Stones]

I am interested to know too!

 

[Garry H (Cut Nut)]

Interesting?
Why?
Gemex samples light return at some specific light zones. I was at a big factory cutting natural diamonds once and they pulled a brilliancescope device apart and measured all the angles for lighting orientation so they could screen the diamonds to supply to users of Gemex from their regular selection. Not always the best looking diamonds - just picking up the specific lighting angles.

 

[monipod]

I'd check out the vendors that list with Rare Carat. There's mixed feelings here about Brilliant Earth, and as it appears you're new on PS, I urge you to do some searches here about BE. Anecdotes withstanding, I don't believe BE offers the best price.

Numbers only tell half the story. I'd invest with a vendor who has a good concierge service to make sure a numbers perfect stone performs well to the human eye.

 

[DejaWiz]

My take: the only value I see in GemEx is highlighting poor light performance of a diamond that is severely clouded or hazy, which you'd be able to immediately see, anyway.

If the measurements and proportions shake out and there are no light inhibiting inclusions/defects, then the GemEx won't reveal any secrets.

AGS and GCAL both complete some degree of light performance assessment and list their findings on their reports...just some food for thought.

 

[finalgears]

Interesting?
Why?
Gemex samples light return at some specific light zones. I was at a big factory cutting natural diamonds once and they pulled a brilliancescope device apart and measured all the angles for lighting orientation so they could screen the diamonds to supply to users of Gemex from their regular selection. Not always the best looking diamonds - just picking up the specific lighting angles.

What should I be looking at to find a great diamond? Just the cut and HCA (which is based on the cut) score?

 

[finalgears]

My take: the only value I see in GemEx is highlighting poor light performance of a diamond that is severely clouded or hazy, which you'd be able to immediately see, anyway.

If the measurements and proportions shake out and there are no light inhibiting inclusions/defects, then the GemEx won't reveal any secrets.

AGS and GCAL both complete some degree of light performance assessment and list their findings on their reports...just some food for thought.

Looking for GIA cert LGD. Should I be looking for AGS and GCAL instead?

 

[DejaWiz]

Looking for GIA cert LGD. Should I be looking for AGS and GCAL instead?

Not necessarily. GIA and AGS can carry pretty hefty price tags, and that higher cost will usually be passed on to the buyer. Does that make sense for a lab grown diamond? ...choice of grading lab comes down to personal preference.

AGS does have slightly stricter standards for proportion measuring and it's harder to get a zero/ideal compared to GIA EX.
The only other (trustworthy) lab that I know of with tight criteria is GCAL, especially to meet their newer 8X spec.

Regardless of grading lab, as long as the proportions, measurements, and angles all play nicely with one another and there are no comments on the report such as:

* Clarity based on clouds not shown.

* Indication of post-growth treatment (as opposed to NO indication of post-growth treatment)...usually only on lower color grade CVD diamonds (worse than J, perhaps...I'm not super versed on post-growth treatment for CVD).

* Blue nuance (or faint blue)...only for HPHT diamonds

Avoid those, and you're sure to find a winner.
I also recommend you look for and avoid diamonds with more than faint flourescence.

Please feel free to post links to the grading reports of any diamonds that you are considering and we would be happy to help offer feedback and advice.

 

[Garry H (Cut Nut)]

Example of a stone that would not pass GEMEX. But is a perfect Tolkowsky proportioned stone. The red rings are missing many of the potential light sources:

 

[DejaWiz]

What should I be looking at to find a great diamond? Just the cut and HCA (which is based on the cut) score?

Stick to the green and adjacent light orange columns:



(chart courtesy of @Garry H (Cut Nut) )