Help! Do these proportions work?

[diamondseeker2006]

Is this stone for yourself? Is it for a pendant or ring? Understand that IGI D or E is not likely to be a GIA D or E.

I don't understand the circumstances regarding the family jeweler unless someone is buying you the stone and they will only buy it from this one jeweler. My opinion is, if they cannot produce a GIA or AGS graded stone within ideal proportions, then thank them and move on!

 

[candyfloss]

It is for myself and for a ring, but it will be bought by someone else. It’s a bit of a complex family situation... do none of those stones work too? I do understand that IGI is more lax with grading which is why I’m looking into the proportions of the stones instead of accepting an “IGI Ideal” at face value. Also why I am sticking to really high colours like D and E so even if it may be lower the stone will still be colourless. Fully aware on how IGI is less reliable though, but was nevertheless hoping for some inputs based on those proportions... Hopefully this clarifies :/

 

[candyfloss]

I feel awful as well about this purchase but it will be a gift and I have been told I can either choose a diamond from that jeweller or just have it be chosen for me. I’ve tried suggesting a change in jeweller but it didn’t go down very well. I don’t quite trust the jeweller enough to have them make the choice, hence why I’ve been digging through their inventory to find something respectable. I have given up any hope of getting a super ideal sort of stone, but just want something respectable and hoped the kind souls here could help with their knowledge >< I’m so sorry about this situation

 

[Dancing Fire]

I feel awful as well about this purchase but it will be a gift and I have been told I can either choose a diamond from that jeweller or just have it be chosen for me. I’ve tried suggesting a change in jeweller but it didn’t go down very well.

Can you change BF?...

 

[candyfloss]

Can you change BF?...

Unfortunately not I’ve been poking around... the proportions of that 0.78ct stone actually looks okay to me, or is there something I’m missing again? It’s at least not a 40.4 pav and it has an okay table, and I’ve seen various combinations on here with 40.5 pav... Strangely though, it’s graded an IGI Excellent, a grade below Ideal

 

[candyfloss]

Sorry pinging this to @Karl_K since I happened to see you were online and I'm really in a bit of a pinch... Could I please seek your opinion on a 55.5% table, 62.6% depth, 35.1 crown, 40.5 pav if you don't mind? The stone will likely face up smaller since it's quite deep too, but would those angles work? My thanks to everyone here for their patience and help!!!

 

[sledge]

Sorry pinging this to @Karl_K since I happened to see you were online and I'm really in a bit of a pinch... Could I please seek your opinion on a 55.5% table, 62.6% depth, 35.1 crown, 40.5 pav if you don't mind? The stone will likely face up smaller since it's quite deep too, but would those angles work? My thanks to everyone here for their patience and help!!!

Not Karl but I believe you are still facing the same problem as before. When the pavilion reaches ~40.45 or lower then obstruction issues are a reality. The lab report value is an average meaning the likelihood of one or more of the 8 actual pavilion angles being 40.45 or less are very high.

To combat that, you need longer (larger) LGF’s, around 85% as Karl pointed out.

 

[candyfloss]

Alas the arrows on this stone are definitely less chunky than the previous one but 85% still seems a stretch since that would likely relate to really thin arrows which isn’t what I’m seeing...

 

[Karl_K]

Not Karl but I believe you are still facing the same problem as before. When the pavilion reaches ~40.45 or lower then obstruction issues are a reality. The lab report value is an average meaning the likelihood of one or more of the 8 actual pavilion angles being 40.45 or less are very high.

To combat that, you need longer (larger) LGF’s, around 85% as Karl pointed out.

correct and thank you for stepping in.
I was just up for a few minutes getting more allergy meds on board at that time.

 

[John Pollard]

I also would not purchase or recommend an IGI graded stone. My reasoning is simple. The purpose of a lab report is to provide confidence regarding the properties of a diamond. Coincidentally the grades on the reports are used to determine market value for a stone. It is known that IGI can be "soft" on their grading, meaning their report may show a D-VS1, but if it were graded by GIA or AGS, it may yield a G-SI1.

Hi @sledge , I hope you don't mind a point of order here. In the global diamond community IGI is considered reputable.

Not to mention, in the past two years, a lot has evolved. There is a new IGI USA President in New York. The lab grown diamond market is exploding and IGI is a leader in that sector. As more and more USA jewelers test the LG diamond water, IGI is getting more direct exposure - and gaining natural market share too.

If you want a general impression you can find 20,000+ IGI grading reports here, accompanied by 360* videos. Of course, video analysis isn't meaningful on a granular level (and many LGD have brown undertone) but it could be useful perspective.

Full disclosure: I've had the pleasure of serving as a diamond cut or education consultant for the major labs over the years - IGI included - and have the blessing/curse of familiarity.

 

[Karl_K]

Hi @sledge , I hope you don't mind a point of order here. In the global diamond community IGI is considered reputable.

Not to mention, in the past two years, a lot has evolved. There is a new IGI USA President in New York. The lab grown diamond market is exploding and IGI is a leader in that sector. As more and more USA jewelers test the LG diamond water, IGI is getting more direct exposure - and gaining natural market share too.

If you want a general impression you can find 20,000+ IGI grading reports here, accompanied by 360* videos. Of course, video analysis isn't meaningful on a granular level (and many LGD have brown undertone) but it could be useful perspective.

Full disclosure: I've had the pleasure of serving as a diamond cut or education consultant for the major labs over the years - IGI included - and have the blessing/curse of familiarity.

I just checked and igi usa is still issuing mounted graded valuation reports with obscene values which in my opinion are not a product a reputable lab should offer.

In mmd igi might be a good choice due to the lower selling costs the effect of grading difference is much less than with
mined diamonds.
But honestly lets say I say igi is ok except for the valuation report, how many people are just going to remember he said igi is ok?

@John Pollard
Your money out of your pocket would you pay the same price without doing your own grading for an igi graded D/IF diamond vs a GIA D/if diamond of similar make and same weight?
I would not.

 

[John Pollard]

I just checked and igi usa is still issuing mounted graded valuation reports with obscene values which in my opinion are not a product a reputable lab should offer.

In the interest of progress - can we keep the focus of this thread on loose diamond grading? (sidebar though, can you send me examples with current dates)

I completely understand what you're saying about "ok except for." With that acknowledged, I also think positives should be recognized.

Your money out of your pocket would you pay the same price without doing your own grading for an igi graded D/IF diamond vs a GIA D/if diamond of similar make and same weight?
I would not.

Collectibles and auction items are marketed with GIA reports. How many pros would pay the same for an AGS or GCAL graded D/IF diamond without doing their own grading? Not many, I wager. GIA has a monopoly in the collectible area - although world record LGDs are being sent to IGI. Actually, GIA has a monopoly in USA loose diamond grading, full stop. It would be nice to see another notable player.

Answering your question in a more common range - yes, based on personal experience, seeing various operations in NY, CA, HK, CN, Antwerp - I have confidence in GIA, IGI, AGS and GCAL loose diamond grading. Answering even more personally - the diamond I helped my brother select for his (now) wife was graded by IGI. And yes, I agreed with the assessment.