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»  » Diamond Prices and Grading »
 » RockyTalky
»  » Whose Diamonds Look Biggest?
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| Pages: 1 of 2: [1] 2 > |
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Whose Diamonds Look Biggest? |
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| P: 6/2/2004 3:04:46 AM | |
Superidealist Ideal Rock Total Posts: 655 Last Post: 8/23/2006 Member Since: 9/10/2003 |
I've searched the inventories of several online vendors and compared the spread index of their diamonds to see who cuts closest to the "ideal" of 6.50mm. The results below show the spread indices for all diamonds between 0.50 and 1.50ct for A Cut Above, Diamond Ideals H&A, Dirt Cheap Diamonds Signature, Nice Ice, and SuperbCert and a representative selection of diamonds of the same size from Blue Nile Signature and Hearts on Fire. 
D Riley |
| Posted: 6/2/2004 3:04:46 AM | |
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There are 56 replies to this message. There are 30 replies on this page. |
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| P: 6/2/2004 3:05:22 AM | |
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Superidealist Ideal Rock Total Posts: 655 Last Post: 8/23/2006 Member Since: 9/10/2003 |
. D Riley |
| Posted: 6/2/2004 3:05:22 AM | |
| P: 6/2/2004 3:07:19 AM | |
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Superidealist Ideal Rock Total Posts: 655 Last Post: 8/23/2006 Member Since: 9/10/2003 |
. D Riley |
| Posted: 6/2/2004 3:07:19 AM | |
| P: 6/2/2004 3:10:26 AM | |
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Superidealist Ideal Rock Total Posts: 655 Last Post: 8/23/2006 Member Since: 9/10/2003 |
. D Riley |
| Posted: 6/2/2004 3:10:26 AM | |
| P: 6/2/2004 3:10:53 AM | |
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Superidealist Ideal Rock Total Posts: 655 Last Post: 8/23/2006 Member Since: 9/10/2003 |
. D Riley |
| Posted: 6/2/2004 3:10:53 AM | |
| P: 6/2/2004 3:11:34 AM | |
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Superidealist Ideal Rock Total Posts: 655 Last Post: 8/23/2006 Member Since: 9/10/2003 |
. D Riley |
| Posted: 6/2/2004 3:11:34 AM | |
| P: 6/2/2004 3:12:00 AM | |
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Superidealist Ideal Rock Total Posts: 655 Last Post: 8/23/2006 Member Since: 9/10/2003 |
. D Riley |
| Posted: 6/2/2004 3:12:00 AM | |
| P: 6/2/2004 3:12:24 AM | |
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Superidealist Ideal Rock Total Posts: 655 Last Post: 8/23/2006 Member Since: 9/10/2003 |
. D Riley |
| Posted: 6/2/2004 3:12:24 AM | |
| P: 6/2/2004 9:00:19 AM | |
moremoremore Ideal Rock Total Posts: 6,825 Last Post: 2/9/2009 Member Since: 3/15/2004 |
got a lot of time on you hands, huh? 
______________________________ Stewart says: I'm good enough. I'm smart enough. And doggon'it, people like me. |
| Posted: 6/2/2004 9:00:19 AM | |
| P: 6/2/2004 9:22:49 AM | |
verticalhorizon Ideal Rock Total Posts: 840 Last Post: 3/24/2006 Member Since: 3/9/2004 |
This is the geekiest thing I've ever seem on PS to date. I love it! 
VH (aka GroomZilla) |
| Posted: 6/2/2004 9:22:49 AM | |
| P: 6/2/2004 9:50:09 AM | |
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moremoremore Ideal Rock Total Posts: 6,825 Last Post: 2/9/2009 Member Since: 3/15/2004 |
LOL...rolling....Luv ya superidealist....
______________________________ Stewart says: I'm good enough. I'm smart enough. And doggon'it, people like me. |
| Posted: 6/2/2004 9:50:09 AM | |
| P: 6/2/2004 10:26:13 AM | |
noobie Ideal Rock Total Posts: 1,318 Last Post: 9/21/2007 Member Since: 3/3/2004 |
Very interesting Dave,
I note that none of the average diameters are above 6.5 mm. Is there anything else that you draw from these numbers? Looking at the graphs, I infer some things, but would be interested to hear from the "experts" and vendors. I guess most of them are in Las Vegas right now, maybe they will comment when they get a chance
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| Posted: 6/2/2004 10:26:13 AM | |
| P: 6/2/2004 10:29:52 AM | |
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verticalhorizon Ideal Rock Total Posts: 840 Last Post: 3/24/2006 Member Since: 3/9/2004 |
It's interesting to see that HoF, one of the most expensive brands, averages the smallest for its carat weight and the largest deviation from ideal.
VH (aka GroomZilla) |
| Posted: 6/2/2004 10:29:52 AM | |
| P: 6/2/2004 10:34:10 AM | |
fire&ice Ideal Rock Total Posts: 7,827 Last Post: 3/30/2009 Member Since: 7/22/2002 |
I think you may need to enter the twelve step spreadsheet progam with my husband. Step away from the spread sheet. that said, I am surprised at how many diamonds are below the 6.5 mark. We make such a big deal about it. Maybe it really is just an average.
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| Posted: 6/2/2004 10:34:10 AM | |
| P: 6/2/2004 10:46:30 AM | |
lop Ideal Rock Total Posts: 2,651 Last Post: 9/7/2009 Member Since: 6/14/2003 |
Ahh the creative mind with insomnia.....interesting stats. I think the variance of some versus the tightness of the spread of others is interesting. Although none of the spreads are so wide that they're really far off the mark.
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| Posted: 6/2/2004 10:46:30 AM | |
| P: 6/2/2004 10:53:26 AM | |
Pricescope Administrator Total Posts: 8,265 Last Post: 1/5/2008 Member Since: 1/1/2000 |
Couple of days ago we ran some stats on the diameter of all 1ct round diamonds listed in the web. About 1/3rd of all 1ct rounds have diameter less than 6.3mm. Pricescope |
| Posted: 6/2/2004 10:53:26 AM | |
| P: 6/2/2004 10:59:25 AM | |
chialea Ideal Rock Total Posts: 520 Last Post: 9/3/2004 Member Since: 4/20/2004 |
wow, thanks, this is really interesting. at the very least, it lets you know who you have to be more or less careful about that sort of thing with :P now if only I can figure out how to explain to my mother than hearts on fire is really not that special, and not worth the premium (given that she has an engineering type for a doting husband)... I guess my SO and I are just going to have to buy an amazingly sparkly engagement ring! no choice here at all. it's a public service.
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| Posted: 6/2/2004 10:59:25 AM | |
| P: 6/2/2004 11:09:29 AM | |
bling Cut Rock Total Posts: 487 Last Post: 5/17/2005 Member Since: 4/17/2003 |
awsome! i love it...
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| Posted: 6/2/2004 11:09:29 AM | |
| P: 6/2/2004 11:11:57 AM | |
Hest88 Ideal Rock Total Posts: 3,670 Last Post: 11/20/2009 Member Since: 1/22/2003 |
Interesting charts, DR. Can you narrow it down to a simpler chart, just plotting a more narrow field of, say, between .95 and 1.25?
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| Posted: 6/2/2004 11:11:57 AM | |
| P: 6/2/2004 11:22:19 AM | |
Paul-Antwerp Ideal Rock Total Posts: 1,902 Last Post: 11/20/2009 Member Since: 9/3/2002 |
Very interesting, although a bit rough. First, one should be aware not to pay too much attention to that exact 6.5-score. A 1.00 Ct-diamond weighs on average 1.0045 (between 1.00 and 1.009). Therefore, you come to a "ideal"-score of 6.5/1.0045 being 6.47, if all other presumptions are correct. Also, the hidden weight in the smaller stones probably has a bigger impact on the score (being percentage-wise bigger) than in the biggest stones. At least, in the variance, this shows a clear difference between the true super-ideals and the wannabees. After all, if you want to buy a brand, you do so because of consistency, and it seems clear that this is seriously lacking with some. Just for fun, I quickly calculated the same for 7 Venus-by-Infinity-stones, without selecting them. Result: 5 times 6.47, once 6.49 and once 6.51, with weights ranging from 0.71 to 1.58. I must admit that I was not surprised. Live long, Paul Slegers |
| Posted: 6/2/2004 11:22:19 AM | |
| P: 6/2/2004 11:36:24 AM | |
aljdewey Ideal Rock Total Posts: 8,236 Last Post: 2/11/2008 Member Since: 11/25/2002 |
I'm a bit fuzzy on the information contained in these graphs. From what is plotted, it appears that you are saying that vendors are offering stones of 1.2 and 1.3 carat weight that only measure 6.5mm?
I find that hard to believe. I must be reading these wrong. My 1.24 ACA diamond meausures 6.97.
_____________________ |
| Posted: 6/2/2004 11:36:24 AM | |
| P: 6/2/2004 11:48:35 AM | |
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dsong1 Rough Rock Total Posts: 36 Last Post: 6/30/2004 Member Since: 5/11/2004 |
I'm confused on how to read this. How do I know where my diamond falls for a 1ct?
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| Posted: 6/2/2004 11:48:35 AM | |
| P: 6/2/2004 12:01:24 PM | |
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Pricescope Administrator Total Posts: 8,265 Last Post: 1/5/2008 Member Since: 1/1/2000 |
AL, Dsong1, it is not a diameter but Superidealist' spread index = (average diameter)/(carat weight)^(1/3) I agree with Paul, although it is fun, do not be too obsessed with this. Table size difference from 54 to 58 can affect spread quite a bit as well. Pricescope |
| Posted: 6/2/2004 12:01:24 PM | |
| P: 6/2/2004 12:25:46 PM | |
valeria101 Ideal Rock Total Posts: 14,048 Last Post: 4/30/2006 Member Since: 8/29/2003 |
---------------- How does this happen? I thought that between two diamonds with identical depth, culet, girdle and diameter, the one with the smaller table is lighter, a bit.  Ana "The greatest experts are only as good as the sum total of what they have seen." [Souren Melikian] |
| Posted: 6/2/2004 12:25:46 PM | |
| P: 6/2/2004 2:26:36 PM | |
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Pricescope Administrator Total Posts: 8,265 Last Post: 1/5/2008 Member Since: 1/1/2000 |
Valeria101:
---------------- Diamond..........#1..........#2 Weight:..........1 ct.......1 ct Table:...........58%........54%
Diameter:........6.51 mm....6.47mm Depth:...........3.92 mm....3.99 mm Crown Height:....14.4%......15.8% Crown Angle:.....34.5°......34.5° Pavilion Depth:..43.1%......43.1% Pavilion Angle:..40.75%.....40.75% Culet:...........Pointed....Pointed Girdle:..........1.0%/2.7%..1.0%/2.7% Pricescope |
| Posted: 6/2/2004 2:26:36 PM | |
| P: 6/2/2004 3:14:49 PM | |
squirerad Cut Rock Total Posts: 120 Last Post: 6/25/2004 Member Since: 4/5/2004 |
Very very interesting. However, I have to say that the human eye cannot differentiate sizes from 6.439 mm to 6.497 mm. More importantly, if one uses more scientific rigors one will find that there is NOT any statistically significant difference between the most "ideal" (SuperbCert) to the least (Hearts on Fire).  The average diameter would be the MEAN and the smallest average deviation represents the STANDARD DEVIATION, which would produce the following spread results:SC 6.473-6.509 ACA 6.478-6.516 NI 6.445-6.515 DI 6.446-6.512 BN 6.422-6.512 DCD 6.398-6.506 HOF 6.373-6.505 As you can see, taking the measurements to just one standard deviation yields no statistically significant differences in the spread of the different brands, i.e., the spread results overlap. SO those who have purchased with any of the brands above should be comforted that their diamond is just as good (in terms of spread) as any other brand. squire "Our country is defined by the rights we protect, and those of us who fought for freedom and put our lives on the line defended the right of people to do things that we disagree with. I would not be pleased to see someone burning the flag because I love the flag, but the Constitution that I fought for preserves the right of free expression." |
| Posted: 6/2/2004 3:14:49 PM | |
| P: 6/2/2004 11:57:46 PM | |
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Superidealist Ideal Rock Total Posts: 655 Last Post: 8/23/2006 Member Since: 9/10/2003 |
---------------- I think this speaks to the quality of diamonds at the sites listed above, since none of the 720 diamonds sampled had a spread index of less than 6.35mm. D Riley |
| Posted: 6/2/2004 11:57:46 PM | |
| P: 6/3/2004 12:09:52 AM | |
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Superidealist Ideal Rock Total Posts: 655 Last Post: 8/23/2006 Member Since: 9/10/2003 |
---------------- I agree, no one should take this too seriously. At best, it is a very crude indication of cut quality. When I started out doing this, my purpose was to see if there was a difference in the spread index of diamonds just shy of and just above the 1.00ct mark. That is, to see if cutters were cutting deeper to break the 1ct barrier. Unfortunately, as you can see from the first graph, there is almost no product out there in the 0.90 - 0.99ct range, so that fell by the wayside. Still, I think it does show something about the different lines.If people were wondering why Infinity and Good Old Gold weren't included, I couldn't find enough of the Infinity stones to make what I thought would be a representative sample and, while there were plenty of stones listed on Good Old Gold, as anyone who has ever visited Jonathan's site will know, it takes forever for each diamond's page to load. This is actually an extension of a similar project I did two years ago. At that time, I compared about 20 diamonds each from several vendors. Paul will be happy to know that Infinity was included and did quite well in the comparison. D Riley |
| Posted: 6/3/2004 12:09:52 AM | |
| P: 6/3/2004 12:14:18 AM | |
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Superidealist Ideal Rock Total Posts: 655 Last Post: 8/23/2006 Member Since: 9/10/2003 |
---------------- Differences become increasingly significant as carat size increases. D Riley |
| Posted: 6/3/2004 12:14:18 AM | |
| P: 6/3/2004 12:16:13 AM | |
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Superidealist Ideal Rock Total Posts: 655 Last Post: 8/23/2006 Member Since: 9/10/2003 |
---------------- If you're interested, let me know and I'll be happy to email you the file. D Riley |
| Posted: 6/3/2004 12:16:13 AM | |
| P: 6/3/2004 12:41:53 AM | |
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lop Ideal Rock Total Posts: 2,651 Last Post: 9/7/2009 Member Since: 6/14/2003 |
I think it's a great test, with interesting results. I've always read that you're eyes really don't discern anything less thatn a .1mm size difference in stones. I don't know if I agree with that -- I think I am more size sensitive than I am color sensitive, but that what the experts have said. None of these samples have more than a .1mm average variance between each other, but all of those 6.3mm and smaller stones do fall into that camp of visually smaller. But, before we go so far as to pass judgement on the various vendors based on the results, I think it's fair to say that some might be optimizing to things other than size when they choose their stock. Size is only one of the "5" c's (assuming you take into account cost). I'd trade off a <.1mm here and there for a great looking stone or a great value. That becomes the interesting part of this whole adventure. Picking that balance that works for your priorities.
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| Posted: 6/3/2004 12:41:53 AM | |
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