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diamond proportions for princess cut


jholland
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Is there a guideline I can follow for Princess cut diamonds. I'm in the market and want to make sure I don't get ripped off. I am looking at a F VS1 with the following dimensions:

table: 60%

total depth: 65

crown angle: 33.5

crown height: 11.8

p. angle: 44.6

p. depth: 51.9

polish: very good

symmetry: very good

culet: none

girdle: thin to medium .7-1.3

fluorescence: none

 

The ideal table % of the princess seems to vary quite a bit. Is a round cut a better option, or is this just a matter of taste. Please give me your opinion!

 

Thanks

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Sorry to ignore you. I figured that one of the diamond dealers here would jump in. It may just be that we're in the middle of a holiday and they are otherwise distracted.

 

Is there a guideline I can follow for Princess cut diamonds.

 

No.

 

At least not one that I count as very reliable. Ideal is a concept the applies to round stones only, and even then it's hotly debated. In the case of princesses, there are a large number of differing opinions about what makes the cut of one stone better than another. It's considerably more complicated. Have you seen this stone? Have you seen other princess cuts in similar lighting environments?

 

Neil Beaty

GG(GIA) ISA NAJA

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"Whereas Princess Cuts or any fancy shape is concerned. "numbers" are absolutely not predictive of diamond beauty.

 

Various combinations of Table-Crown-Pavillion will yield a beautiful stone.

 

The best advice I can give you is look at as many Princess Cuts of various 'number' combinations as possible and determine which are most pleasing to you.

 

If you're shopping on the Internet, the minimum and excellent requirement IMO, is a light performance analysis such as provided by Gemex Systems (www.gemex.com).

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If you're shopping on the Internet, the minimum and excellent requirement IMO, is a light performance analysis such as provided by Gemex Systems (www.gemex.com).

 

Barry,

 

I have to disagree about BrillianceScope being a minimum requirement.

 

Although Gemex reports are both interesting and useful, they are only available on a tiny percentage of the stones in the marketplace because of the company’s proprietary system and their limited distribution. There is a vast array of beautiful stones that do not have one of these reports and where the dealer has no sensible way of getting one. Colored reflector images like the Idealscope, Firescope, H&A viewers and ASET tools are more limited in the information they provide but they are far more readily available and can be moderately predictive of how the stone will look in normal lighting conditions. Your first piece of advice is dead on. Look at the stones. For internet purchases, I highly recommend two key steps that may not at first be obvious.

 

1) Choose your dealer carefully. There are lots of them out there that are selling superficially similar goods for pretty similar prices. Don’t go strictly on the prices. Customers do not all have the same requirements and good communication with the dealer is critical to getting what you want the first time. Any good dealer will offer you a complete refund if you are unhappy with your selection but neither of you is anxious to have to do this. Finding a dealer that suits your style of communication can do wonders towards making this a painless transaction.

 

2) If you aren’t a diamond expert, hire someone who is to assist you. Independent appraisals aren’t generally very expensive relative to the cost of your diamond and the vast majority of customers find the experience to be very useful as part of their shopping experience. This is true of all diamonds but especially so with fancies. Experience is very helpful. It’s quite difficult for a consumer to get into a position where they have carefully examined even a few diamonds of a particular shape. Most IA’s have seen and thoroughly inspected hundreds.

 

Neil Beaty

GG(GIA) ISA NAJA

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Make sure, if you don't want to end up with a dud diamond, to look at the diamonds yourself. Pick what you think is pretty to your eye whether it be round or princess cut. You may find that you like even another type of shape if you actually go and see some diamonds your self. Don't rob yourself of the experience of shopping and looking at diamonds and trying on mountings versus a price and a few numbers on a piece of paper. That is what diamond stores are for, browsing, learning, and getting service. There really is no substitue for looking and learning.

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Brillianscope analyses are becoming more prevalent by the day. To date, over 800,000 diamonds have been analyzed and scanned into the Gemex database. A growing number of internet vendors have the technology in house. Having worked with this technology over the past four years, it is IMO, the best out there at the present time.

 

H&A scopes are not relevant to princess cuts.

 

I would stay very clear of the Aset scope at this time. In the first two weeks since it's debut at the Vegas show it has been shown to lack reliablity and standardization as slight differences in stone placement and diamond size will significantly alter the results.

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A growing number of internet vendors have the technology in house.

 

Growing it is, but it's still a very small percentage of the available stones. I can't say I have the statistics at hand and please let me know if you do but I would surprised if more than 1% of the stones currently being offered for sale have Brilliancescope data available. Although many of these stones are quite lovely, the presence or absence of a BS report is not a good predictor of the quality of a stone.

 

H&A scopes are not relevant to princess cuts.

Agreed.

 

I would stay very clear of the Aset scope at this time. In the first two weeks since it's debut at the Vegas show it has been shown to lack reliablity and standardization as slight differences in stone placement and diamond size will significantly alter the results.

 

I agree that this is an unproven tool and that there is a considerable margin for error based on how the image is taken. This doesn't make it useless but it's important to avoid making conclusions based on the information presented just because someone would like it to show more than more than it does. So far, even fewer dealers are using this than are using the Brilliancescope so it has this same problem of being barely used. I expect this to change fairly rapidly as it enters the marketplace and the question of what can, and what can not be learned from the pictures becomes more clearly understood. My gut feeling is that this tool will be more useful with fancy shapes than it is with rounds but I've seen very little information on this so far. I do not use an ASET in my own examination proceedures at the moment but I am actively watching how it progresses. I do own one. :blink: Idealscopes, Firescopes and similar devices have similar issues with interpreting the images but I do think there is useful information in them. Unfortunately, both buyers and sellers wish that they told more than they do. I’m with Jan, the only way to really tell is to actually look at the stone and to compare it with others. These various tools are moderately useful for making a pre-examination estimation when it’s not possible to see the stone itself but I would rank them all as less useful than buying from a credible dealer who can personally examine the stone and discuss the issues thoughtfully. Actually, they may have a secondary benefit. The dealers that are forthcoming with information to try and help their customers make an informed decision tend to be the best dealers. The fact that they are offering this sort of thing, along with certificate scans, sarin reports, and photomicrographs may serve as a useful clue about which dealers should be considered.

 

 

Neil Beaty

GG(GIA) ISA NAJA

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Neil;

 

You agree with me that the Aset scope is..."I agree that this is an unproven tool and that there is a considerable margin for error based on how the image is taken. This doesn't make it useless."

 

Unproven, considerable margin for error, no operator control exerted by the manufacturer, and yet you say "it doesn't make it useless"?? C'mon, Neil.

 

If I read correctly, you were one of the people on another diamond forum that punched some serious holes into this aset-scope.

 

Again, if the consumer has the opportunity to work with a vendor and physically examine the diamond(s), that is the optimal situation.

 

Shopping on the Internet, various scopes and photo's are most helpful and beneficial.

Working with a reputable vendor that has the diamond(s) in-house is the correct way to go and will insure a good purchase experience.

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Thanks for the responses!

 

Although being new to this process I can't say I fully understand all your answers.

 

I have looked at the diamond, and compared it with other princess stones. Even though it seems to be an excellent stone I have actually decided to go with a round stone.

 

Carat weight and cut being about equal, the round cut looks much bigger, and proportions seem to be more agreed upon by experts.

 

I know it's impossible to completely know without seeing the stone for yourselfs, but tell me what you think about the specs on this stone compared to the other- Just really want to know if anything jumps out as major flaws or obvious differences in the quality of the stones(on paper):

E, VS2, and both are .91

Measurements:6.28-6.31 X 3.80mm-the princess cut was width 5.52 length 5.65 L/W 1:02

Table:63%

Depth:60.4%

Girdle: Medium to Sl thick Facedted (is being faceted a problem?)

Culet: None

Crown angle:34.8

Crown Height: 15.6

Pav. angle: 40.7

Pav. depth: 43.1

Proportion: Excellent

Fluorescence: None

Polish: Excellent

Symmetry: Very Good

 

Thanks again

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That is exactly the problem. No one here can tell you how beautiful a diamond is going to be without seeing it based on a few average external measurements. Many diamonds measure the same but look completely different.

BTW rounds sparkle more than any of the other shapes if well cut.

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If I read correctly, you were one of the people on another diamond forum that punched some serious holes into this aset-scope.

I punched holes in some attempts to draw conclusions that I thought weren’t merited. This is not the same as saying that there is no useful information available, only that that what is available is less than some people were hoping for. I haven’t come to any conclusions about the usefulness of the images yet. I’m still collecting data. It’s reasonably likely that I have more experience at taking these pictures than anyone outside of AGS and, as mentioned in my prior post, I don’t use them in my own analysis procedures. I’m still learning about them and I fully expect this investigation to take months. By the way, AGS lab doesn’t use them either.

 

None of these tools are intended to replicate real world lighting and viewing conditions. They are designed to feature a few particular attributes that are presumably useful. The restrictions that the stone should be meticulously cleaned and viewed with one eye from a position perpendicular to the table are, for example, quite limiting. Although diamonds are occasionally seen from this position, it is hardly the only observation of importance. This does not mean that this isn’t useful information but it’s hardly ‘real world’ conditions and it’s not intended to supply enough information for someone make a definitive purchase decision. It’s just another piece of the puzzle.

 

Neil Beaty

GG(GIA) ISA NAJA

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I hear you, Neil. Just very puzzling with all of the inability to accurately interpret what actually the images from the aset scope are saying, why AGS would be strongly marketing this device to retail jewelers at this time.

 

Bill Caudill even has a plethora of diamonds with different number configurations color-mapped with this gizmo.

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I don't think AGS has thought this all the way through. The tabletop version, which isn’t available yet and costs $1,000 improves quite a few of the inherent problems with the way the image is created that I was discussing in that other thread but it definitely doesn’t eliminate all of the issues and I still haven’t seen much information on interpreting the data. I agree that this seems like a curious omission. I’m reasonably confident that, if this is going to become a widely used tool, it will be the handheld model because of the price tag and surely they know this. This is especially true since there is no apparently way to tell the difference between an image taken with the handheld unit and an image taken with the tabletop unit. Perhaps I’m missing something. I think they were anxious to release things at the JCK show because of this race they’ve been having with GIA over cut grading and they don’t yet have their ducks in a row. Personally, I think this was a strategic mistake and it’s going to end up making them look less than professional but I’m definitely not an AGS insider and their plans may be moving along swimmingly. . My guess is that it’s selling briskly to the AGS stores but I can’t imagine that very many others are buying it beyond the seriously hard-core types (I bought one, Rhino did too. There are a few more like us). They may be limiting their thoughts on interpretation to the AGS stores in order to give them a competitive head start before the internet people get involved. Good luck with that.

 

That poster with all the images of round stones is pretty and perhaps even useful. I don’t have one and it’s not available, at least not yet. I think it was part of the booth display but Jim said they would be selling it soon. I’m also fairly sure that those are computer generated images and not actual diamonds. My general feeling is that tool this is going to be more useful for fancy’s than rounds anyway so I’m not sure what that will be good for beyond interesting office décor but rest assured, I’ll buy one as soon as it becomes available and you will undoubtedly come across my opinions of it. It behooves me to stay up on these things.

 

Jholland,

Sorry to hijack your discussion with minutia about arcane gemological tools. You’ve received good advice above. The parameters you’ve given are well within the possibility of a lovely stone although a 63% table is slightly large for the classic definition of ‘ideal’. No, the faceted girdle is not a problem. This stone is well worth considering.

 

Neil Beaty

GG(GIA) ISA NAJA

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Agree. IMO AGS's race with GIA has led them into committing a very bad strategic mistake of releasing this new scope before it has been sufficiently tested and de-bugged.

 

A major shortcoming is the absence of a standardized procedure whereby consumers can be confident that images from any retailer or internet vendor can be duplicated with consistency and reliability and thus telling the same story. Their credibility has taken a major hit.

 

I believe this will become more apparent in the weeks and months to come as consumers become exposed to the vagaries of this situation.

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I hear they will be losing quite a bit of business from their current clientel due to this error in judgement.

We'll see how it plays out.

 

As I mentioned above, AGS lab does not use these images on any of their reports and the tools to generate them are not part of their new grading system. They aren't even mentioned. These are coming from AGS and a whole new operation called the 'AGS advanced instrument division', which I gather is a wholly owned subsidiary of AGS (AGSL is an entirely different company where AGS, many AGS members as well as many others are stockholders). It's intended as a tool to help the AGS members to try and guess which stones will be likely receive the coveted AGS-0 grade from the lab. No doubt the dealers will also be using it as a sales tool to try and explain some of the concepts of diamond optics. This is not coming from AGSL although many of the people who don't care for this sort of tool are holding it against them because of their tight relationship and similar name to AGS. I don't understand the tools or the new AGS grading system well enough (yet) to give an opinion as to whether they will be useful for this purpose. I must admit, I 'm not yet convinced.

 

Neil Beaty

GG(GIA) ISA NAJA

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With diamond prices continuously going up ( the next price increase following the most recent diamond sight is about 4-6 weeks away) consumers will not be inclined to part with thousands of their hard-earned dollars on a diamond based on a gizmo that "guesses" about a diamond's quality and worthiness to purchase.

 

IMO, unless AGS takes some quick corrective actions, this aset-scope has all the makings of the second coming of the Edsel.

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"...consumers will not be inclined to part with thousands of their hard-earned dollars on a diamond based on a gizmo that "guesses" about a diamond's quality and worthiness to purchase."

 

Like BrillianceScope for example.

 

"...unless AGS takes some quick corrective actions, this aset-scope has all the makings of the second coming of the Edsel."

 

That's very possible. Do you remember the GIA Proportionscope? How about the Okuda scope? Not all ideas are good ones but even bad ones can have a few seeds that turn out to be useful later. It's difficult to know too much although some bits of information are more useful than others.

 

By the way, Edsel's are highly collectable and very expensive.

 

Neil Beaty

GG(GIA) ISA NAJA

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No, Neil, definitely not the Brilliancescope. (www.gemex.com).

 

The Brilliancescope, whether you accept it or not, has a clearly defined user protocol that is strictly controlled by Gemex Systems which guarantees and assures consumers that all diamonds scanned on this machine regardless of who the Operator is or which machine anywhere in the world is used, will give results that are consistent and repeatable. Intra-machine and Inter-machine; the results will be the same every time. Scanned results are carefully examined and reviewed by Gemex engineers and if approved, THEY print the laminated report, not the OPERATOR. Over 800,000 diamonds have been scanned by the Brilliancecope and currently reside in the Gemex Systems diamond databank. Diamond manufacturers, wholesalers, and retailers in the U.S.A., Antwerp, China, India, and Israel are using this machine with great success. Gemex Systems is a growing company with a technology that more consumers are identifying with every day and using in their diamond purchase decisions.

 

The aset-scope has no defined ( by AGS ) user protocol, and it's operation and results are at the whim of the operator. It's validity is unknown, there is serious disagreement as to what the colors signify in terms of light performance, and it's repeatability and consistency of "results" from the images I have seen thus far are highly questionable.

 

The Edsel may indeed be an expensive "Collector's Item", but I don't see any on the road, do you?

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None of which advances it beyond "… a gizmo that "guesses" about a diamond's quality and worthiness to purchase."

 

You’re arguing that it’s a better gizmo than the current incarnation of the ASET; that the reports are more repeatable, that the information included in them is more useful and that the documents are more difficult to alter or counterfeit. I agree with all of this but it still doesn’t replace actually looking at the stone and the presence of a favorable looking BS report does not make a stone worth purchasing any more than the lack of such a report means that it’s not. It’s useful information that allows a customer or dealer to make a more educated ‘guess’ prior to actually seeing the stone. I have no problem with the BS reports or the information included in them but I think you’re giving them more credit than they are due.

 

Neil

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I am consistently on record both on this forum and other diamond forums as advocating that the optimal situation is to physically see and examine the diamond.

 

But for those consumers who do not the have the time or the ability to visit their retail jewelers and personally examine diamonds, but shop via internet diamond websites, the Brilliancescope is currently the best technology available with which to "see" and evaluate the diamond(s).

 

This Brilliancescope report used in conjuction with a lab report, photo's, and Cut grade analyses, offers the consumer much useful information on which to base their purchase decision. It is more than just a "guess". I have used this technology over the past four years and can vouch for the dovetailing of it's results with that which the eye sees.

I know you don't have any experience with the Brilliancescope nor do the others that critique it.

 

It also bears mentioning that the Brilliancescope results corroborates beautifully and directly with Idealscope images; the Idealscope being a favorite of the anti-Brilliancescope crowd.

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