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John NC

Round Stone- Final Step, Best Compromise? Table, Depth, Clarity And Color Compromise, Iga Vs. Egl

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Sorry meant GIA in the heading...

Hi there- I've been lurking on the site for a while, and appreciate the education--- invaluable.

I'm close to purchasing and would like to ask for a bit of last minute advice, just not quite secure in my thoughts.

I'm looking at round diamonds, going in a solitaire setting, in the 2 carat range. Budget is going to be around $13K including the setting ($375 range). I know it's hard to get a great diamond in that price range, but I think (hope) I've hit a good compromise, which is what I need help with. Minimums I've been looking at are G/H in color and VS to SI-1 in clarity, very good to premiun/ ideal cut and very good to ideal polish/ symetry. If it's a GIA diamond I would consider a color of I- is this sound thinking? GIA comes with a higher price but I understand there are assurances there as well.

 

GIA/ AGS vs. EGL- Looks like GIA/ AGS are the best in that order, followed about 2 steps behind by EGL? In fact I've been told that EGL diamonds will rate about 2 steps behind GIA in color and clarity, so that an GIA graded H, SI-1 diamond most likely will be a J, I-1 by EGL standards? That's a bit scary if true, and EGL's cut standards are not as stringent as GIA?

 

Many diamonds I've looked at on this site aren't graded at all... but their numbers look great for the money- where are they getting their grades from, the cutter/ wholesaler? What's the caveat to these diamonds- they look like a gamble but if you luck out and they hit the numbers it would be a great find?

For instance this one: 2 carat G, VS2 Depth 61.3% Table 59% no flourescence, very good symetry and polish, no info on girdle, no cutlet, 8.00 x 8.14 x 4.95- $11,843... not graded by EGL/ GIA/ AGS.

 

Table/ Depth- I've been told that the ideal depth is 60-63%, and the ideal table is 53-59%? If this is true, then what are the ideal numbers in that range to maximize fire/ brilliance/ scintillation? Ideal polish and symetry I'm sure play into this as well?

 

I prefer no to light flourescence, and no to a very small cutlet, and for the girdle thin to medium and faceted seems best? Many in my price range are thick, is that OK? Just seems like hidden weight around the middle.

 

As far as color and clarity go, which is more important? For instance which diamond would be better- a VS with H color, or a SI with G color?

 

Took Amanda to the mall to look at diamond shapes and settings, and out of about 40 diamonds 2 really impressed us, brought tears to her eyes actually, and made me wide-eyed... so I gotta get this right. Those two mall diamonds were beautiful, but seemed overpriced for what they were... both 1 carat, $10K mounted G/H in color, SI-1 in clarity and excellent/ ideal cut based on their grading system, not GIA/AGS/ or even EGL. They had the light spectrum analysis reports and all that, but again the grading bodies I'd never heard of. So I started doing additional research and ran across abazias, bluenile, union, excel, etc... and the hunt has been on.

 

Thanks so much for any advice, words of caution or reality checks.

I'll be happy to report back on which diamond I buy/ which setting/ and which company I go with, how much it costs, and how the experience goes for future buyers.

Thanks again!

John

Edited by John NC

John, Southeast NC

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Hello John, welcome!

 

My comments in bold below.

 

Hi there- I've been lurking on the site for a while, and appreciate the education--- invaluable.

I'm close to purchasing and would like to ask for a bit of last minute advice, just not quite secure in my thoughts.

I'm looking at round diamonds, going in a solitaire setting, in the 2 carat range. Budget is going to be around $13K including the setting ($375 range). I know it's hard to get a great diamond in that price range, but I think (hope) I've hit a good compromise, which is what I need help with. Minimums I've been looking at are G/H in color and VS to SI-1 in clarity, very good to premiun/ ideal cut and very good to ideal polish/ symetry. If it's a GIA diamond I would consider a color of I- is this sound thinking? GIA comes with a higher price but I understand there are assurances there as well. Have you seen a properly graded (GIA/AGS) G, I and K diamond? Nothing wrong with any of the above, in fact a fair number of people like the warmer white of a K more than the pure white of an F, but no one can tell your preference (or Amanda's!). Also, since your budget is not huge (for what you seem to be looking to get, that is), I would recommend that you come up with clear priorities in terms of the 4Cs. My order for a round brilliant solitaire would be Cut, Carat, Colour, Clarity. For example, I'd suggest you look at excellent cut diamonds in the 1.75-1.80 range, rather than a less well cut 2.00.

 

GIA/ AGS vs. EGL- Looks like GIA/ AGS are the best in that order, followed about 2 steps behind by EGL? Yes, and No. GIA and AGS grading is reliable enough to be used as the reference; EGL is simply "another opinion". In fact I've been told that EGL diamonds will rate about 2 steps behind GIA in color and clarity, so that an GIA graded H, SI-1 diamond most likely will be a J, I-1 by EGL standards? Not necessarily; they may be spot on for clarity, but loose on colour, or vice versa, or... part of the problem with a non GIA/AGSL grading is precisely that you don't know where you stand. That's a bit scary if true, and EGL's cut standards are not as stringent as GIA? Unfortunately yes.

 

Many diamonds I've looked at on this site aren't graded at all... but their numbers look great for the money- where are they getting their grades from, the cutter/ wholesaler? What's the caveat to these diamonds- they look like a gamble but if you luck out and they hit the numbers it would be a great find? If there is no lab, you are basically trusting the manufacturer or the retailer to provide you with that information. As long as you can trust them, there's nothing wrong with that. For a diamond of the type you are considering, though, I would not feel safe without a GIA or AGSL report on it

For instance this one: 2 carat G, VS2 Depth 61.3% Table 59% no flourescence, very good symetry and polish, no info on girdle, no cutlet, 8.00 x 8.14 x 4.95- $11,843... not graded by EGL/ GIA/ AGS. You pays your money, you gets your choice. MY money would remain firmly in my bank account.

 

Table/ Depth- I've been told that the ideal depth is 60-63%, and the ideal table is 53-59%? If this is true, then what are the ideal numbers in that range to maximize fire/ brilliance/ scintillation? Diamond proportions are quite a complex affair; after all the thing has 57 facets, and all of them need to play their part. One thing is for sure: you won't find any hard and fast rule that involves only a couple of numbers to identify the best performing diamond. Add to this that even in terms of the balance of reflected and refracted light (brilliance vs. fire), tastes vary, and your "ideal balance" may be quite different from mine or the jeweller's. You really need to look at as many diamonds as possible and come up with your own rules Ideal polish and symetry I'm sure play into this as well? To some extent yes, but far less than proportions

 

I prefer no to light flourescence, and no to a very small cutlet, and for the girdle thin to medium and faceted seems best? It's culet. Leave cutlets for the kitchen. Fluorescence is a matter of personal taste: some like it, some don't; culet size should be minimised in modern round brilliant cuts, and girdle thin to medium is fine. Faceted or bruted is not particularly important. Many in my price range are thick, is that OK? No Just seems like hidden weight around the middle. Yes

 

As far as color and clarity go, which is more important? For instance which diamond would be better- a VS with H color, or a SI with G color? Each to his own. My personal preference is colour over clarity, as long as the stone is eye clean. However many are uncomfortable with the thought of their future Mother-in-Law approaching the diamond with a loupe and finding - shock, horror - a crystal or a feather.

 

Took Amanda to the mall to look at diamond shapes and settings, and out of about 40 diamonds 2 really impressed us, brought tears to her eyes actually, and made me wide-eyed... so I gotta get this right. Those two mall diamonds were beautiful, but seemed overpriced for what they were... both 1 carat, $10K mounted G/H in color, SI-1 in clarity and excellent/ ideal cut based on their grading system, not GIA/AGS/ or even EGL. They had the light spectrum analysis reports and all that, but again the grading bodies I'd never heard of. So I started doing additional research and ran across abazias, bluenile, union, excel, etc... and the hunt has been on.

 

Thanks so much for any advice, words of caution or reality checks.

I'll be happy to report back on which diamond I buy/ which setting/ and which company I go with, how much it costs, and how the experience goes for future buyers.

Thanks again!

John

Good luck. Tell us how you get on!


Davide - Specialised Consumer Information and Assistance,
Diamonds by Lauren (http://www.diamondsbylauren.com)
davide@diamondsbylauren.com

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I would avoid in-house color/clarity gradings.

 

Insofar as the EGL's is concerned, EGL-NY is the best of the bunch.


Barry
www.exceldiamonds.com
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Great info, thank you so much David(elevi) sp? and Barry.

I agree Cut is #1, then Color, then Clarity. Saw a 2 carat J, I-1 ungraded, mall diamond that was terrible (looked like it had spilled milk on it) for $6,300. Then at the same store a 1 carat G/H, SI-1 ideal cut that was awesome for $10K... of course it was graded in house so who's to say.

That's kinda where I've gotten my color G/H and clarity SI-1 guidelines from, and am now adding all the cut percentages and polish/ symetry/ culet (none)/ girdle (medium) preferences to the mix.

For an excellent cut, what do you think about a 57-59% table width? Seems like that would maximize the face-up size of the diamond, and I believe I read that GIA reported that a 59% table width maximizes sparkle? I may be out to lunch on that one but I swear I read that.

Culet, yes... not cutlet. No culet is the way to go.

What about "Very slight graining"? Is that a biggie?

OK to maximize fire sparkle and brilliance... what are some good tight tolerances to keep in mind as far as depth and table percentages, and crown height and pavillion depth percentages?

And is it a big deal if an EGL diamond states "Tolkowsky Ideal Cut" and "8 Hearts and 8 arrows", as well as "Conflict Free". Sorry for all the quotation marks, just wanted to be exact in my wording.

I'll step down into the 1.8 range and see what looks good in the GIA/ AGS graded diamonds, but any advice on those percentages would be greatly appreciated.

Thanks! John... confused but learning.


John, Southeast NC

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John - I commented on part of your questions on another thread (http://www.diamond.info/forum/index.php?showtopic=4753). Just wanted to add a couple of things on the bits in quotes:

 

"Very slight graining" is most likely nothing to worry about - it simply means that the surface of the diamond shows sign of the crystal structure, most likely as very fine parallel "scratches" which are totally invisible to the naked eye and pretty difficult to detect with a 10x loupe. However, the term "very slight" is subjective and it may vary between labs (and graders within the labs).

 

"Tolkowsy Ideal Cut" is an interesting term. Tolkowsky's recommended cut proportions - dating back to 1919 and using what today is an unacceptably simplified model - are for a table of 53%, pavillion angle of 40.75 and crown angle of 34.5 However, since Tolkowsky didn't really specify one cut as ideal but identified a number of sets of proportions that worked to produce nice looking diamonds; the interesting bit is that if one uses the ranges of proportions in those sets to cut a stone, one can produce truly horrible results as well as very nice ones. See here (http://www.gia.edu/research/1383/2280/article_detail.cfm) for more details.

 

"8 Hearts and 8 Arrows" means very little. It means that using particular lighting conditions a pattern of 8 arrow-like shapes is visible on one side of the diamond, and a pattern of 8 heart-like shapes is visible on the other side. Sometimes this can be taken as a sign that the diamond cut has been done with care, but it's no guarantee of a good cut.

 

"Conflict free" is another marketing gimmick. Most diamonds on the market are traced through what is known as the Kimberley process (http://www.kimberleyprocess.com/) to ensure the supply of rough diamonds is not directly involved in funding war or violence in the extraction zones. If you want to make even more sure that is the case, buy an estate piece, an Australian diamond or a Canadian one. Having said that, there is no guarantee that the retailer that just sold you a nice Argyle pink won't use the funds to support a warlord in Angola... so I'm not sure what the point of the "Conflict Free" claim is.


Davide - Specialised Consumer Information and Assistance,
Diamonds by Lauren (http://www.diamondsbylauren.com)
davide@diamondsbylauren.com

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Thanks Davidelevi... great info. I mentioned I read that GIA has recently suggested that a table width percentage of 59 yields a more brilliant diamond, and I read that on this site's tutorial info, shown here (Tolkowsky cut):

Depth percentage: 59%

Table percentage: 53%

Crown height percentage: 16%

Pavilion depth percentage: 43%

Girdle thickness: Medium and even all the way around the diamond

Symmetry: Perfect

Perfectly aligned and formed facets

Very small or absent culet

It should be obvious that finding a Tolkowsky diamond is an expensive undertaking. To complicate matters even more, recent studies by the G.I.A. have demonstrated that a 59% table yields a more brilliant diamond (as opposed to Tolkowsky's 53% specification). Jewelers tend to confuse the issue even more, since their version of the "ideal cut" will likely vary from day to day, as their diamond inventory changes.

 

OK, to complicate things further, each website quotes a different grading body or theory. Blue nile says it's signature ideal is:

60.1- 61.9% depth and 55-57% table.

Then there's the american ideal cut that says 53-58% table, 58-62.3% depth... and so on.

 

What are the basic numbers a round buyer should keep in mind, for instance the search function on this site, for instance I've been using 58-63% depth and 54-59% table. Does a smaller table % and larger depth percentage make the diamond long? And a higher table and lower depth make it shallow? In that range what's a good solid combo, or does my range need tweeking?

Saturday we looked at some in house jewelry store graded diamonds (local reputable store but still). They didn't have a report and were in house graded H color SI-1 clarity- very nice looking diamonds even when compared to a hearts on fire diamond they had in the store..

I write that because then I go to this site and pull up EGL G color, VS-2 to SI-1 diamonds, and the rep from the respective company tells me that the diamond in reality could be I even J in color and I-1 in clarity! Very scary... another online rep told me that EGL might be off 1/2 a step in color OR clarity, usually not both. What's the deal with EGL and how close will the cut, color, clarity be to GIA/ AGS?

 

I know it's a gamble not going GIA, but how can I get the best value out of an EGL diamond? I thought I'd get 2 of the best my budget will allow shipped to me and hope that they're both awesome and I can pick the one that gets me fired up, or at least one is awesome? HELP! Thanks- John


John, Southeast NC

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Oh I meant to reiterate what EGL diamonds I've been checking out... round G/ H... VS-1- SI-1 EGL... trying to keep it to excellent polish and symetry, no to light fourescence, no culet, medium girdle (although a few have slightly thick but all else looks good). 58-63% depth (should I cut that back to 62% depth?) and 54-59% table... I know the 8 hearts/ 8 arrows isn't a big deal, but it does give a bit of assurance that the symetry is there.

For instance what's wrong with this stone?

8.45 x 8.45 x 5.22 mm

depth % 61.9

table % 57

crown height 14%

pavillion depth 44%

Graining- Nil

girdle slightly thick (I know not ideal and hidden weight)

no flourescence or culet

VS-2, G, EGL Excellent Ideal Cut, 8 Hearts/ Arrows.

I know if you can't see it in person hard to tell, but just by stats anything jump out as off? Thanks, John


John, Southeast NC

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John;

 

The bottom line is that you may be able to paint by the numbers but you certainly can not and should not buy a diamond just by the "numbers". A diamonds face up sparkle is affected by more than just the table, Crown, and Pavillion. The upper and lower girdle facets play a critical role in light refraction and slight differentials in their angle and facet size may be the difference between a great face up diamond to a mediocre one. Therefore, within the Towlkowsky definition of ideal, you can have two diamonds with the same numbers face up differently.

 

If you're shopping in person, trust your eyes to be your guide and look at the diamonds in different lighting environments. Don't suffer paralysis by over-analysis by fixating on the numbers as she will be wearing the diamond on her finger, not the lab grading report.

 

If you're shopping on-line you will definitely need more than the Vendors definition of "Signature" or "Ideal" and need to obtain data and measures of light performance and the Vendor's own in-person examination and evaluation.

 

The diagram below highlights the working facets that all contribute and are critical in maximizing a diamonds face-up beauty.

post-5339-1234818359_thumb.jpg


Barry
www.exceldiamonds.com
@Exceldiamonds on Twitter

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Big ditto!

 

The big issue with the "ranges" theory is that it is incomplete (e.g. no mention of lower and upper girdle). Use your ranges (which are fine for that purpose) to filter out obviously badly cut stones. Then it's up to your eyes (and your wallet)


Davide - Specialised Consumer Information and Assistance,
Diamonds by Lauren (http://www.diamondsbylauren.com)
davide@diamondsbylauren.com

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OK guys, I'm wearing myself out but I'm close...

I switched over to look at some GIA/ AGSL diamonds... and here are 3 that I came up with, round brilliant 2 carats... or slightly over, not less.

 

1) GIA I color, SI-1,Polish and symetry excellent, cut grade excellent, no flour. 55% crown , 61.8% depth, 35 degree crown angle, 40.8 degree pavillion angle, no culet, thin to medium girdle.

 

2) AGSL 2.5 rating (I) color, 5 clarity (SI-1), cut grade AGS Ideal (0) 58.9% crown, 60.5% depth, 32.6 degree crown angle, 41.1 degree pavillion angle, slightly thick to thick girdle, no culet.

 

Almost identical in price...(#1 and #2)... around $14K and change.

 

About $2,500 less:

3) GIA H, SI-2, polish and symetry very good, no flour. cut 'premium' 59% crown, 61.4% depth, 37.5 degree crown angle, 40 degree pavillion, girdle medium to thick and faceted, no culet.

 

To confuse things even further what about this EGL (not us EGL)... same price as 1 and 2 around $14K.

4) EGL D, SI-1, polish good to very good, and symetry very good, no flour. 53% table, 59.2 depth, 14% crown height, 43% pavillion depth, girdle medium/ faceted, no culet, 'Tolkowsky Ideal Cut' for what it's worth... is this a shallow cut?

 

Which one looks like a winner? I know you can't tell until you see them, I might have a couple shipped to me and have an appraiser take a look with me.

 

Also do you put much stock in the pricescope cut adviser? Seems like an informative 'test', and shocking when I think I have a candidate and I put the stats in there and it gets a bad rating outside of GIA/ AGS ideal and excellent ranges.

Thanks- John

http://www.pricescope.com/cutadviser.asp


John, Southeast NC

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HCA as per its inventor Gary Holloway is a reject tool, not a pick tool. It only measures (rounded off)17 of the 58 facets.


Barry
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A couple of them look like big bets to me:

 

#3 (odd angles) and #4 (I would NOT buy an EGL-International 2 ct stone from an unknown vendor; plus, there is a reason why GIA and AGSL I/SI1 stones are the same price as an EGL-I D/SI1).

 

Could I be wrong? Very possibly, particularly on #3 - it has uncommon proportions, but it could be excellent value and a very firey stone.

 

To be honest, I think you are at the stage where you can't select winners - you can only winnow out losers (and even then, you can only select likely losers with the data you have, not be certain they are losers). I would suggest that you take a look at these and see which one(s) you like the look of; based on the info above you have picked 4 stones that are likely to look very different from each other, and your (and your FI's) taste definitely should come into the choice.

 

What do the vendors say? Have they got the stones in stock?


Davide - Specialised Consumer Information and Assistance,
Diamonds by Lauren (http://www.diamondsbylauren.com)
davide@diamondsbylauren.com

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Hi guys, thank you so much for your help. I'm still very confused... dealing with the online vendors is tough, they usually don't have the diamonds in stock so you're basically just reading stats and looking at grading reports.

I know using the range theory isn't the best bet in the world, but if you were sorting just using the available stats what #'s would you use?

For instance I've been using 58-62 depth % and 54-59 table %... and have been leaning towards 58-60 depth and 56-59 table, trying to maximize the face up size while retaining as much light reflection as possible? As far as the crown height % I read that 14.3-16.3% was ideal and pavillion depth 42.8- 43.2% was ideal... not sure how that equates to angle but I'd love to hear your preferences. I read another poster's note that pavillion depth less that 38% is no good and over 40% is no good.

Barry you mentioned in a post that 60-61% table is preferred- that seems like a higher number than what I've read?

Blue nile lists as "signature ideal" 60.1- 61.9 depth %, and 55-57 table %.

If you had to give a good strong starting point using depth and table percentages, and crown and pavillion percentages and angles what would you say to use? I know that's just a start and 2 diamonds could be totally different, but I want to start with sound fundamentals, then narrow down by the details (polish/ symetry/ culet/ girdle/ flourescence), and go from there.

Thanks so much- John


John, Southeast NC

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Hi guys, thank you so much for your help. I'm still very confused... dealing with the online vendors is tough, they usually don't have the diamonds in stock so you're basically just reading stats and looking at grading reports.

I know using the range theory isn't the best bet in the world, but if you were sorting just using the available stats what #'s would you use?

For instance I've been using 58-62 depth % and 54-59 table %... and have been leaning towards 58-60 depth and 56-59 table, trying to maximize the face up size while retaining as much light reflection as possible? As far as the crown height % I read that 14.3-16.3% was ideal and pavillion depth 42.8- 43.2% was ideal... not sure how that equates to angle but I'd love to hear your preferences. I read another poster's note that pavillion depth less that 38% is no good and over 40% is no good.

Barry you mentioned in a post that 60-61% table is preferred- that seems like a higher number than what I've read?

Blue nile lists as "signature ideal" 60.1- 61.9 depth %, and 55-57 table %.

If you had to give a good strong starting point using depth and table percentages, and crown and pavillion percentages and angles what would you say to use? I know that's just a start and 2 diamonds could be totally different, but I want to start with sound fundamentals, then narrow down by the details (polish/ symetry/ culet/ girdle/ flourescence), and go from there.

Thanks so much- John

 

In my opinion you are too shallow on depth. I would stay 60-62% total depth. Also you will do a little better with pavilion angle versus percentage. It might help as well if you use a vendor that can view the stone for you and run some light performance analysis versus just going by numbers as well.


Jan

For those that want to know the truth about diamonds, just ask.

 

dbof.com

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John;

 

I have reviewed my responses to you and don't see anywhere advocating that 60-61% table is preferred. Just the opposite.

 

I have been very clear to indicate that you can not judge a diamond just by the numbers and suggested that if you're intent is to shop on-line that you do so with a vendor(s) that can actually have the diamond in front of them.


Barry
www.exceldiamonds.com
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Hi Barry- Sorry I took that quote out of context. It was from "Considered a perfect cut?" back in '04. I've read the comments on this site front to back and have found all the opinions quite helpful.

The diamond the man asked about (below) had a shallow depth and wide table, and you were telling him that and his diamond was too wide and shallow and to get the table percentage down?

Here's the thread-

http://www.diamond.info/forum/index.php?showtopic=1235

 

 

He asked if this was a good cut:

 

.91ct

depth 59.5%

table 63%

VS1

color: E

polish symmety: good/good

girdle: thin to thick, faceted6.22 - 6.28 x3.72mm

fluorescence: none

cutlet: none

 

What you wrote: This combination of table and depth percentage indicate a shallow stone that is prone to light leakage and indeed allowed the cutter to achieve the final carat weight of .91 which brings a significant price premium over a .80-.83 carat stone, which a proper cut would have yielded.

 

Had the cutter brought the table in to a preferable 60-61%, it would have resulted in less light leakage, more light refraction through the Crown and Table to your eye and made for a better looking diamond.

 

Barry

Exceldiamonds.com

Diamondvues.com

 

(John NC now) I've been using some dimension guidelines to select candidates then plugging the info into the HCA simulator to see how they perform.

http://www.pricescope.com/cutadviser.asp

I understand the HCA simulator is more a tool to narrow down rather than to select winners... but it seems like a neat way to check out a diamond on a rudimentary level.

 

OK- still looking for a 2 carat round (or a bit bigger)... H color, SI-1 or 2, very good or better polish and symetry, no to light flourescence, no culet, medium girdle... great cut and great proportions...

If you were stocking your store with 2 carat rounds, what depth and table percentages would you start with? I was thinking 56-59 table and 59-61 depth... at the high extreme 60% table. Read a lot of debates about the 60/60 diamond too...

Here are some numbers I've seen- might not be exactly accurate, my research folder is a bit messy (and thick).

A. Fishman and Son wrote that they prefer a combination of 59.5% depth and 58/59% table.

GIA is very broad at 58.6-63% depth and 52.4-59% table.

Abazias lists 60-63 depth and 53-59 table, again very broad.

Blue Nile- 60.1- 61.9 depth and 55-57 table...

Tolkowsky indicates 59% depth and 53% table, but to me 53% table seems too small?

So what's a good baseline combo? I know this has been asked over and over, but if you were stocking your store what would you start your search with? If you want to share angle preferences and other info that would be great as well.

I'm close!

Sorry for the long posts... just looking for the light at the end of the tunnel.

Regards,

John


John, Southeast NC

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John, a couple of comments:

 

1. I think Barry meant "Had the cutter brought the depth in to a preferable 60-61%"...

 

2. Bear in mind that the "old cut" diamonds widespread when Tolkowsky wrote his book had small tables and high crowns. Taste and habit no doubt played a role in his choice. By the way, if you look at the range of stones that he considered wonderfully cut, you get tables from 46.9 to 61.3 and depths from 55.4 to 61.4 - a range so broad that it goes way beyond anything that GIA, AGS or anyone else today would consider "indicative of good performance". Bear also in mind that Tolkowsky wrote his book 90 years ago, and quite a few things have changed, beginning from the ability to cut diamonds much more precisely in a highly repeatable fashion.

 

In terms of "the combo" - you keep asking the same question, and getting the same answer: there is no such thing. Partly because the two parameters that you select (which are the ones most commonly specified) are not particularly meaningful in isolation, and partly because different combos will have different looks - none "better" but all different - and you may like one more than the other. Cost and availability also enter the equation.

 

If you really want to use parameters rather than photos, reflector technologies of different types or someone's eyes to narrow down the search, start from GIA excellent or AGS 0 cut grades - not ranges for table and depth%. At least this way you get a combination of a several geometrical parameters that is (mostly) guaranteed to work decently.

 

ETA - FWIW - Tolkowsky considered the pavillion angle the most critical proportion, finding angles between 40 and 41 degrees to work best. This is still a useful benchmark, but it's NOT a substitute for looking at the diamond.

Edited by davidelevi

Davide - Specialised Consumer Information and Assistance,
Diamonds by Lauren (http://www.diamondsbylauren.com)
davide@diamondsbylauren.com

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John;

 

Good summary by David.


Barry
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Hi guys,

Yes seems like I'm beating a dead horse over this depth and crown percentage issue, and I know that with each combo there are optimal crown and pavillion angles... thanks for all the feedback.

I do agree that the eye is the most important judge, after of course all the other parameters check out.

Thanks- John


John, Southeast NC

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Trust your eyes. She'll be wearing the diamond on her finger, not the GIA report.


Barry
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http://www.diamond.info/forum/index.php?showtopic=4753

 

Hi folks, just wanted to post this link to Cathy's post. It's very informative and I've posted several comments there and so have the pros. She's in the 2- 2.25 carat range just like I am. Her jeweler provided her a diamond that she is finding iffy, and she found one on Bluenile that looks like a great deal although the proportions aren't ideal according to certain schools of thought? Very informative and she should be posting the diamond she decides on soon.

Thanks- John

Oh and I'll be posting the diamond I decide on as well FYI.


John, Southeast NC

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Trust your eyes. She'll be wearing the diamond on her finger, not the GIA report.

 

Blast that laminated paper - you can't even fold it in a graceful bow. :)

 

John - this may come too late in the day, but I was re-reading this and other recent threads (wonderful thing, being at home with flu), and I just noticed something. You seem(ed?) to assume that the bigger the table % the bigger the stone would look. That's not true for two reasons:

 

1) The table % is a relative measurement of how much of the top surface of the diamond is taken up by the table. At the extreme, a diamond without a crown would have a table % of 100%, but it could still be smaller visually than a diamond of the same weight with a 53% table (see the graphical examples I attach - exaggerated, but they make the point)

 

2) A diamond is by and large a complicated set of mirrors - you see a mirror if it reflects something. If the mirrors work properly and direct the light towards your eye, then they seem bigger than a set of mirrors that scatter the light in all different directions.

 

So, from #1, look at spread, not table: the diameter of the diamond matters. From #2, look at cut, of which table is only one (and not the most important) part.

post-11046-1236184938_thumb.jpg


Davide - Specialised Consumer Information and Assistance,
Diamonds by Lauren (http://www.diamondsbylauren.com)
davide@diamondsbylauren.com

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Hi David, Thanks! I didn't mean to imply that a larger table percentage indicates a larger appearing diamond, I do get it (now) but may have been confused then. Spread is the indicator of width as well as the actual total width measurements... Of course you want that spread to be balanced by the proper depth and crown/ pavilion angles... throw in a dose of excellent polish and symetry and you're on the right track?

I'm having trouble trying to find a good GIA round with excellent cut and at least very good polish and symetry, 2 carat +, with no to very slight flourescence... SI2 or better, G/H color, maybe I color- for the money- under $12.5K or so. I found a couple but the proportions seem a little odd then I plug them into the HCA and WAM they come back with 3.5, 4.5 or the like. Seems like Cathy might have found herself a good one, even though like (I think you?) said some purists might not agree that the numbers are ideal, but heck seems like a deal to me, and if it has great fire/ brilliance- that's it!

ROUGH! Is there a particular day of the week that's good to look online? Maybe a rush of diamonds coming onto the open market on Mondays or Thursdays for instance? I guess I'm going to try to find some of the luck Cathy was struck by.

Thanks- John


John, Southeast NC

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"I'm having trouble trying to find a good GIA round with excellent cut and at least very good polish and symetry, 2 carat +, with no to very slight flourescence... SI2 or better, G/H color, maybe I color- for the money- under $12.5K or so."

 

John;

 

Tougher to find than a needle in a haystack. Check the diamond database and you will see that these specs sell for considerably more. If you do find one at 12.5K there is a good red flag reason for it.


Barry
www.exceldiamonds.com
@Exceldiamonds on Twitter

Excel Diamonds on Facebook

sales@exceldiamonds.com
1-866-829-8600
1-212-921-0635

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