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Round Diamond Measurements


althomas
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I am looking at GIA Round Diamonds sizes 1.15-1.49 with a color of I-D and VS1-VVS1 clarity. I was wondering if you could tell me what a good depth and table percentage was as well as good measurements. Finally, I think that the cut is the most important aspect to a diamond sparkling and wanted to know if there was a huge difference between an excellent versus ideal cut in GIA standards. What is the most important aspect to look at in terms of the cut? symmetry of the facets? Thanks for your help

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I agree that cutting is the most important of the 4 C’s and it’s a more complicated question than can be answered with simple table & depth measurements.

 

GIA doesn’t use the grade ‘ideal’ although AGS does. AGS-ideal is a considerably narrower range than GIA-excellent and they tend to sell at a premium of about 5-10% so most stones that are eligible will get sent to AGS for that reason. Whether this difference is important or even better to you has a lot to do with taste. The GIA system is much more inclusive of different preferences although they exclude some lovely stones as well. ‘Most popular’ is not always the same as ‘best’. Always the most important thing to look at is the stone, not the grading report but if you're using the reports to decide which ones are worth considering and you aren't using the GIA or AGS assigned cut grade, the most important things to look at are the crown and pavilion angles and how they relate to one another.

 

I would not consider 'ideal' from anyone else as a relevant question.

 

1.15/I/VS1 - 1.49/D/VVS1 is a pretty big range. Perhaps we can help you narrow that down a bit if you give us some of your priorities. What's your budget?

 

Neil

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I am looking at GIA Round Diamonds sizes 1.15-1.49 with a color of I-D and VS1-VVS1 clarity. I was wondering if you could tell me what a good depth and table percentage was as well as good measurements. Finally, I think that the cut is the most important aspect to a diamond sparkling and wanted to know if there was a huge difference between an excellent versus ideal cut in GIA standards. What is the most important aspect to look at in terms of the cut? symmetry of the facets? Thanks for your help

 

 

It depends on the individual diamond. You won't be able to tell how sparkly the diamond is going to be by a couple of average numbers on a lab report. Not all ideal cuts and GIA excellent cut diamonds perform the same. There is quite a range in light performance in the top cut grades. Some get much higher light return than others. If I was going to pay a premium for an ideal cut, I would want the one with the highest light return for the money.

 

For more info on that go to :

www.gemex.com

www.isee2.com

 

If you need help in finding a stone with the high light return, send me an e-mail with your budget and we'll help you find one for the best price.

brokersj@bellsouth.net

 

Regards,

Jan

Edited by jan
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I agree, my range is large. I am trying to figure out what the largest diamond I can with an excellent cut. The most important thing to me is how well it is cut and therefore sparkles. Ideally, I would like a 1.5 diamond, but realize there is a huge price difference when going to the 1.5 carat mark. From what I have seen many diamonds that are about 1.19-1.25 look similar in size to a 1.5 carat diamond. Therefore, I am willing to have a clarity and color level that is on the low end of my range so that I can get a diamond with the perfect cut. I have about 10k to spend on a diamond, but would like to spend somewhere about 8k or so. Do you think that is possible? From what I have seen it looks to be possible. I am now trying to figure out how the symmetry, polish and flouresance fit into the picture. When you said the crown and pavillion were the most important, how do you determine if they are good?

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There’s kind of a cool utility at www.facetware.gia.edu that helps you relate some of the various dimensions on stones to the cutting.

 

For the most part, polish and symmetry don’t affect the cutting although there are limits to this. Stick with Very Good or better on the GIA grade with these two and I think you’ll be fine. Sometimes you can even get into ‘Good’ with these and still have a stunning stone.

 

Fluorescence is a mixed bag. I rather like it but it’s not really very popular and consequently drives down the prices a little bit. To me that’s a feature but it depends on you. If you pay the premium for very high color (D/E) I would go for no fluoro but if you’re aiming for a price point and are dropping color to get there (H-I), I would be happy with up to medium and maybe even strong if it got me where I wanted to go.

 

One of the realities of the world is that very few environments have significant UV content to the light and outside of the disco or the tanning salon you will never notice it. I see people regularly with fluorescent diamonds that they’ve owned and worn for years and never even noticed.

 

Given that set of requirements, I would include VS2 and maybe even SI1 clarity in your search. That should get you over your 1.50 weight point and still be within your budget. At your high end of D/VVS1 you aren’t even close, even if you drop the size to 1.00.

 

Neil

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If you'd like t post the price, I'll be happy to give you my honest assessment of it.

 

Also if you have not seen the stone- we'll also need to wait for your impression of it.

Many people have no objection whatsoever to a slight tint in a diamond.

But if you are someone who does, and it's a "low I" color- you might notice a tint.

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If you looked at an I grade stone loose, sideways, lying face down on a white surface under diffused UV-filtered white light (the way colourless diamonds are graded for colour), most people would see a slight tint. These conditions are designed to help the grader discriminate faint tones of yellow and brown by minimising the amount of reflected/refracted light coming from the stone. BUT:

 

1. In real life, you look at the diamond face up in a setting. In a well cut stone, there is so much light coming back at you that you are not likely to see the body colour of the diamond in most conditions, plus if the stone is set in a white metal there will be more "white" reflected from the metal.

 

2. Colour sensitivity varies from person to person, and you may not see an 'I' body tint anyway.

 

3. Blue fluorescence may also help to decrease the yellow tint in some conditions (not in the case of this stone, since it has none)

 

The only way to know if an I stone has a tint for you in real life is to look at one - preferably next to other higher grade stones and in as many different lighting conditions as you can - and come up with your own personal conclusion.

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I looked at two diamonds I really liked today and wanted to get an opinion on what a good price would be. I was told the pre-discounted price on the first was 11357 and on the second was 8975. I could care less about the clarity, but I really think the excellent cut grade made a big difference. How much could I get the jeweler to come down?

 

 

Round Brilliant

 

Measurements: 6.99 - 7.04 x 4.32 mm

 

Carat Weight: 1.29

 

Color Grade: H

 

Clarity Grade: VS1

 

Cut Grade: Excellent

 

 

 

Proportions: Depth: 61.6 %

 

Table: 57 %

 

Crown Angle: 36°

 

Crown Height: 15.5 %

 

Pavilion Angle: 40.8°

 

Pavilion Depth: 43 %

 

Star length: 50 %

 

Lower Half: 80 %

 

Girdle: Thin, Faceted

 

Culet: None

 

Finish:

 

Polish: Very Good

 

Symmetry: Excellent

 

Fluorescence: None

 

 

 

Comments: Additional clouds are not shown.

 

 

 

 

Round Brilliant

 

Measurements: 6.88 - 6.94 x 4.34 mm

 

Carat Weight: 1.29

 

Color Grade: I

 

Clarity Grade: VS2

 

Cut Grade: Very Good

 

 

 

Proportions: Depth: 62.8 %

 

Table: 57 %

 

Crown Angle: 35.5°

 

Crown Height: 15.5 %

 

Pavilion Angle: 41°

 

Pavilion Depth: 43.5 %

 

Star length: 55 %

 

Lower Half: 75 %

 

Girdle: Thin to Slightly Thick, Faceted

 

Culet: None

 

Finish:

 

Polish: Good

 

Symmetry: Very Good

 

Fluorescence: None

 

 

 

Comments: Additional clouds are not shown. Surface graining is not shown.

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I looked at two diamonds I really liked today and wanted to get an opinion on what a good price would be. I was told the pre-discounted price on the first was 11357 and on the second was 8975. I could care less about the clarity, but I really think the excellent cut grade made a big difference. How much could I get the jeweler to come down?

 

How long is a piece of string?

 

I'm not asking the following expecting a public answer on the forum, but these are all factors that will matter:

 

Who is the jeweller? Where is the store located? Does the jeweller own the stones outright, or are they on memo/loan/virtual listing? How long have they had them in stock for? How much did they pay for them? What return/trade-up/cash-in policies and guarantees do they offer? Are you purchasing the setting there as well? If so, how much are you paying for it?

 

Online, similar stones go for about $1500-$2000 less than the quoted price; expect to end somewhere between the two, since the B&M jeweller has higher costs.

 

You - rightly in my view - don't care about VS2 or VS1 clarity, but the trade will. Difference between a 1.3 ct H/VS1 and I/VS2 is about 20%, all else being equal.

 

BTW - FWIW, the "very good" cut grade on the second stone may only be due to the polish grading, since GIA will not issue an "excellent" cut grade to a stone with less than "very good" polish, no matter how good the proportions. Arbitrary? Yes, but they had to draw a line somewhere.

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I could care less about the clarity

 

If you don’t care for the difference between VS1 and VS2, I would call that a deal killer for the VS1. Like it or not, this is part of the price and, if you don’t value it then you are paying extra for something that is of no value to you. A good price on the wrong thing is no bargain.

 

Don’t take this as an editorial suggestion, but why have you ruled out SI1? The same issues apply over the VS2/SI1 decision. If you don’t care, it’ll save you quite a bit of money to step down a grade. Most correctly graded SI1's in that size range do not have eye visible inclusions.

 

 

BTW - FWIW, the "very good" cut grade on the second stone may only be due to the polish grading, since GIA will not issue an "excellent" cut grade to a stone with less than "very good" polish, no matter how good the proportions. Arbitrary? Yes, but they had to draw a line somewhere.

 

There’s kind of a cool utility at www.facetware.gia.edu that can help you estimate if the proportions fall within a particular GIA grade without considering the polish/symmetry issue. I don’t want to take the time to data enter the subject stone but it’s free and anyone who wants to can do it themself.

 

Neil

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