Got Diamond Questions?
Our community of diamond experts are here to provide answers
Sign in to follow this  
rich051

Considered a perfect cut?

Recommended Posts

I've asking myself for a week now if I had made the right purchase and am looking for some advise out there. I purchased last week an engagement ring for my girlfriend of 3 years. One of my major concerns to make sure I purchased a diamond with a perfect cut. When I looked at the stone it appears to have some fire to it and not that much and as I have surfed through the web looking at depth and table % on what determine a perfect cut they have varied. The jewelry store states that it fits within the proportion guidelines but I have some doubts and am looking for others opinions. The details are below and thanks in advance. Do you think I shoud exchange it when I still have the chance or do you think I may be a little too critical? -Rich

 

.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

Share this post


Link to post
Share on other sites

Hi Rich,

 

Well I can tell you outright that it’s not a "perfect cut" but that does not mean that it’s a bad diamond. It all depends on what you want and what are the most important factors to you. If it's an "ideal cut" that you’re after, then my advice is to continue looking.


www.UnionDiamond.com

"Your trusted online diamond source"

Share this post


Link to post
Share on other sites

Rich - the table percentage is pretty far outside of what the AGS considers "Ideal", so you may want to continue to look around.

 

Be careful with jewelry stores because the "pretty lights" can often trick the eye into thinking that the diamond has fire and brilliance, when in reality, it doesn't offer much of those things at all. Work on the mathematical breakdown first. Have you considered shopping the web?

Share this post


Link to post
Share on other sites

Hi, Rich. This should help. First, there's no such thing as a *perfect* diamond that is in the price range of us mere mortals. :blink: Having gotten that off my chest, I do have a diamond certificate from GIA, so I do know *something* about diamonds.

In the last few months, the standards have been expanded. IMHO not good at all. So, these are the current (old) guidelines for round cut diamonds. Each shape has its' own guidelines.

Ultra Ideal: depth: 58.7-62.4% table: 53-58% polish: excellent symmetry: excellent

Ideal: depth: 58.4-62.9% table: 53-60% polish&symmetry: ex to very good

Premium: depth: 57.9-63.5% table: 53-63%

Good: depth: 57.5-63.8% table: 51-64%

Average: depth: 57-65% table: 51-69%

Poor: depth: <57 or >64% table: <51 or >69

These #'s are always on the certificates and are proportional - my prefered cut falls 1/2 way between the ultra ideal with depth of 61 and table of 57. You also need to consider the crown angle-30-35 degrees, girdle- uniform - thin to medium; (a too thick girdle catches dirt and makes the stone look dark), culet-none or pointed, flourescence-none, and pavillion depth-less than 38% is not good and 40% or more is not good, so I choose 1/2 way more or less based on all the other factors. Not all certificates contain all this info, either. Then there's color! D is the whitest possible *perfect* color, but most people can't really see the color differences in D-E-F (top colors) and color's always personal. Clarity: The cleanest you can possibly afford is the closest to *perfect* IF then VVS1, VVS2, VS1, VS2, SI1, SI2, I1, I2,

So, there's your mini course in buying *perfect* diamonds :D The best I can tell you is ask a jeweler you trust for the cleanest, whitest diamond available in your price range (because it's value will not depreciate) OR choose several smaller "D"/"IF" stones and do an invisible setting design and get a GIA or EGL certificates to always be certain the diamonds are NOT clarity enhanced and that requires a certificate.

Buying a diamond for a lifetime is usually emotionally exhausting - I hope this helps, if you have more questions, let me know, and by all means this is not everything there is to know about diamonds, but maybe it will help.

Good luck, congratulations, happy marriage.

jennaE

PS: your diamond falls into the "premium" range, the same E color in ultra ideal will cost several thousand dollars more.

Share this post


Link to post
Share on other sites
Each shape has its' own guidelines.

Ultra Ideal: depth: 58.7-62.4% table: 53-58% polish: excellent symmetry: excellent

Ideal: depth: 58.4-62.9% table: 53-60% polish&symmetry: ex to very good

Premium: depth: 57.9-63.5% table: 53-63%

Good: depth: 57.5-63.8% table: 51-64%

Average: depth: 57-65% table: 51-69%

Poor: depth: <57 or >64% table: <51 or >69

Hi Rich,

 

There are quite a few different definitions of 'perfect' or 'ideal' and this causes a fair amount of confusion, even among jewelers and appraisers. It's important to know what the seller means when they use this kind of term. The above list is not used by any of the major labs or appraisal groups. Personally, I've never found the depth measurement to be particularly indicative of the optic properties of a stone although it's useful in identifying a particular stone for appraisal purposes.

 

If you love the stone and it sings to YOU, that's the point. Second guessing about the optics and terms like 'ideal' can be a mistake because it leads you to miss the point. It's ok if you're into this kind of analysis but it's hardly necessary. Is it beautiful? Does it make your beloved feel loved when she sees? That's what it's for. The rest is details.

 

Neil Beaty

GG(GIA) ISA NAJA


Neil Beaty

GG(GIA) ICGA(AGS) NAJA

 

There's never a crowd when you go that extra mile.

Professional Appraisals in Denver

Share this post


Link to post
Share on other sites

The numbers and percentages in the list I gave were taken directly from my GIA diamond essentials and diamond grading manuals, as well as EGL and AGS grading criteria. The new greatly expanded guidelines established for consumers are not part of the above. "If it looks good" is not the way to buy a diamond - you could be buying rose cut, fisheyes, single cut, glass, CZ's, fakes of all sorts, stones with flat bottoms, clarity enhancements, nicks, scratches, missing facets, extra facets, stones that'll break at the slightest glance, the list goes on and on. Personally, I would NEVER trust anyone who says "if it looks good" that's all that counts. This is why the industry has established guidelines - to prevent getting ripped off. The AGS and GIA both use guidelines, don't let anyone tell you different. The "details" ARE the point, which is why the question was asked in the first place. The Federal Trade Commission also has many stipulations on how a diamond can be described - required reading.

So who's going to buy their next home on the basis of "if it looks good"?

Next car or truck?

DON'T buy a diamond this way either.

jenna

Share this post


Link to post
Share on other sites

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
www.exceldiamonds.com
@Exceldiamonds on Twitter

Excel Diamonds on Facebook

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

Share this post


Link to post
Share on other sites
The numbers and percentages in the list I gave were taken directly from my GIA diamond essentials and diamond grading manuals, as well as EGL and AGS grading criteria.

jennae,

 

I'm not familiar with the content of the GIA diamond essentials class and so I can't speak for what it contains. The system you've described is not used by the GIA lab, EGL-USA lab or the AGS lab as a way of describing stones on any any of their reports. As you point out, it also does not match the new proposed systems from either GIA or AGS. EGL overseas labs use their own systems and they do use some of the same names as on your list. Perhaps there is one that uses your system.

 

AGS has a scale although it's not particularly similar to the one you describe.

EGL-USA uses similar words on their reports but, again, it's not using your parameters or even a variant of them. In both cases, they consider crown and pavilion geometry to be important. I agree.

 

GIA does not issue a cut grade on any of there present reports.

 

None of the above labs use the word 'perfect' to describe anything, nor did they before the FTC directive limiting this was published in 2001. The FTC guidelines restrict the use of the word 'perfect' to describing clarity. Their guidelines for describing cut are interesting but are nothing like your scale. I agree that people selling diamonds should read these rules but I'm not so convinced that they will be helpful for consumers. For those who are interested, here. they are.

 

IMO, simple Table% and Depth% are not sufficient information to make any meaningful conclusions about cut quality of a gemstone.

 

I think the most important attribute of a house (at least a house that you plan to occupy) is deciding if you like it and would like to live in it. Details matter but focusing on one particular trait while ignoring others can be a serious mistake. Focusing on the details and buying a house that you hate because the numbers look good is foolish.

 

Neil Beaty

GG(GIA) ISA NAJA


Neil Beaty

GG(GIA) ICGA(AGS) NAJA

 

There's never a crowd when you go that extra mile.

Professional Appraisals in Denver

Share this post


Link to post
Share on other sites

If you had an GIA report only to make your decision, would a technically 'perfect' cut round diamond have a depth between 58.7-62.4% and a table between 53-58%. Is this correct? Given a medium girdle with no cutlet and ex/ex polish and symmetry

 

I was under the impression that a table near 59% is suggested by GIA and 53% is suggested by Tolkowsky.

 

Excuse me, if i sound ignorant. I'm just confused about table %.

 

Of course I realize that there is more to a technically 'perfect' cut than just those numbers and that a technically 'perfect' cut may lack light performace which is probably more important to your soon-to-be wife then technicals on paper.

Share this post


Link to post
Share on other sites

These percentages sound strikingly like those in Dave Atlas's AGA charts, which can be found here:

 

http://www.diamond.info/diamonds/diamonds_4cs_cut5.shtml

 

GIA is moving away from recommending specific table/depth %'s and will be issuing actual cut grades based on actual measured light return.


"Fish and Visitors stink after three days"

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this