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Size difference


tvanparys
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I am looking to buy a diamond for the setting I have.

 

My current Girl Friend has tried on rings before, and loved the center stone when it was a .67

 

I have been told that you can have a .64 to .67 and not really see the difference once in the setting

 

is this true?

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To some extent that’s true. A single point is rather small. Two points is twice as big but still pretty small. 200 points is quite a lot. It’s like asking ‘Which raindrop was the one that made it a storm?’

 

This is further complicated by the fact that when her friends see her diamond and comment on how big it looks, they are talking about diameter, not weight. A very shallow 0.64 will face up larger than a deep 0.67. The correct size is a balancing act of quite a few variables. Pick a size you like and don’t get hung up on the weight (or even worse, diameter) because this leads to buying stones with poor cutting. Go for a stone with good light performance and that you like the look of.

 

Neil Beaty

GG(GIA) ISA NAJA

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how can toy tell if a stone is shallow?

The stones she's looking at must of ranged something like 5.50mm to 5.70mm in diameter. Take into account that cut is never really spot on it was probably something like 5.45mm to 5.65mm. This is a small difference to one's eyes, especially so if the cut proportions of the .64 stone are better than that of the .67 stone.

 

You really need to take into account all the details of these diamond to decide what's best. For all you know the .67 might have a thick girdle hiding all that extra weight below and thus looking smaller than it should (more depth = less width).

 

I would not bother with the size difference here as it's minute, but rather get the best cut, color, clarity option you can.

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For an idea of how round diamond size increases with carat weight you can view the comparison chart I've made at the following link below

 

what link?

 

I was violating forums rules by giving you a link so what I've done is I've included the chart image within this thread also.

 

DiamondCaratSizeScale.JPG

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Some consumers on the other forum mentioned problems with this chart even after they allowed for modifications pertaining to their computer screen and diamond.

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Some consumers on the other forum mentioned problems with this chart even after they allowed for modifications pertaining to their computer screen and diamond.

This is odd, for a valid comparison they need to make sure the 5cm line on their screen is indeed 5cm wide by measuring it.

 

Providing such one can measure the diamond's shown and they will reflect the width in mm that such a ideal cut carat weight diamond shall expose.

 

What I'm thinking is they're using a low XGA resolution or worst still a low resolution and have a large monitor.

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Just for reference ...

 

Here is a .61ct next to a .65ct representing a .04ct difference. Both are comparably cut stones and as you can see there is little size difference....

post-2-1117304801.jpg

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However weight differences do not always equate to size differences. Ie. Here is a 1.01ct diamond next to a .81ct diamond. A .20ct weight difference with little to no size difference due to a poop cut on the 1.01ct.

 

The only way to accurately determine these size differences between the 2 stones you've listed is to at least get a total depth% measurement which should be easily attainable either through the lab report or a Sarin. Of course the more info the better.

post-2-1117305007.jpg

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Just for reference ...

 

Here is a .61ct next to a .65ct representing a .04ct difference. Both are comparably cut stones and as you can see there is little size difference....

Right, a minor difference indeed especially if we take into consideration that this photo is enlarged and we don't normally look at diamond's so close (well unless a girl has jut got one for the first few weeks :)

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However weight differences do not always equate to size differences. Ie. Here is a 1.01ct diamond next to a .81ct diamond. A .20ct weight difference with little to no size difference due to a poop cut on the 1.01ct.

 

The only way to accurately determine these size differences between the 2 stones you've listed is to at least get a total depth% measurement which should be easily attainable either through the lab report or a Sarin. Of course the more info the better.

And we can see how the 1.01ct has less brilliance than the 0.81ct as a result also.

 

All the weight under the girdle in the former makes for a too deep diamond (this one's probably about 64-5% right Rhino?) and so the light isn't bounced back through the top (this due to the pavilion facets being at the wrong angles!?!?).

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However weight differences do not always equate to size differences.  Ie. Here is a 1.01ct diamond next to a .81ct diamond.  A .20ct weight difference with little to no size difference due to a poop cut on the 1.01ct.

 

The only way to accurately determine these size differences between the 2 stones you've listed is to at least get a total depth% measurement which should be easily attainable either through the lab report or a Sarin.  Of course the more info the better.

And we can see how the 1.01ct has less brilliance than the 0.81ct as a result also.

 

All the weight under the girdle in the former makes for a too deep diamond (this one's probably about 64-5% right Rhino?) and so the light isn't bounced back through the top (this due to the pavilion facets being at the wrong angles!?!?).

Ew... YOU'RE GOOD MAN. You in the trade or just a cut geek consumer? :P

 

That stones total depth % is precisely 64.8%. It's crown/pavilion/table combo is 38.7 crown angles, 41.7 pavilion angles and a 63% table. Here is a lightscope image demonstrating how closelly this resembles shit... taki mushrooms. B)

 

Whites = leakage

blacks = light being returned at high angles (75-90 degrees) (very little in this case)

reds = reflective facets at other angles less than 75 degrees.

 

Most effective light return is that which reflects at 45 degrees and higher. This article from GIA expounds on it a little more. http://www.gia.edu/research/1383/10135/article_detail.cfm

post-2-1117310851.jpg

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However weight differences do not always equate to size differences.  Ie. Here is a 1.01ct diamond next to a .81ct diamond.  A .20ct weight difference with little to no size difference due to a poop cut on the 1.01ct.

 

The only way to accurately determine these size differences between the 2 stones you've listed is to at least get a total depth% measurement which should be easily attainable either through the lab report or a Sarin.  Of course the more info the better.

And we can see how the 1.01ct has less brilliance than the 0.81ct as a result also.

 

All the weight under the girdle in the former makes for a too deep diamond (this one's probably about 64-5% right Rhino?) and so the light isn't bounced back through the top (this due to the pavilion facets being at the wrong angles!?!?).

Ew... YOU'RE GOOD MAN. You in the trade or just a cut geek consumer? :P

 

That stones total depth % is precisely 64.8%. It's crown/pavilion/table combo is 38.7 crown angles, 41.7 pavilion angles and a 63% table. Here is a lightscope image demonstrating how closelly this resembles shit... taki mushrooms. B)

 

Whites = leakage

blacks = light being returned at high angles (75-90 degrees) (very little in this case)

reds = reflective facets at other angles less than 75 degrees.

 

Most effective light return is that which reflects at 45 degrees and higher. This article from GIA expounds on it a little more. http://www.gia.edu/research/1383/10135/article_detail.cfm

I'm just one of no doubt many interested in diamonds.

 

63% is a very large table and without even looking at the other diamond specs I bet the price of the above 1.01ct is no more than then 0.81ct also shown above?!?!. I'm not going to try and guess the actual price as I don't know the clarity or color though I'm tempted to say the color is ~H (G at most) and the clarity is SI1/VS2 at most. Can't be too sure but the 0.81ct seems of a better color grade than the 1.01ct by 1 color grade (on the border of colorless/near colorless).

 

OK so I know the depth is also way off but still, from what I've seen large tables pinpoint a lower price, just as do thick girdles (not talking square cuts of course) and say large culets.

 

Speaking of tables I can't see how anyone can enjoy such large tables given that a) it puts the crown angles too steep for "best of" light performance and B) it might be just me but aesthetics play a lot in a diamond's beauty. As to the latter the crown facets will be too steep to give it that elegance or panache in appearence.

 

 

BTW, checked out your site, very nice. You're one of few to show actual zoomed in images of clarity grades plus a wealth of other info (makes for an enjoyable read).

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Rhino,

 

Is ths part of a mushroom collection?

 

I see stones like this fairly often but I'm a little surprised that you have one floating around.

 

Neil Beaty

GG(GIA) ISA NAJA

LOL... While on the net we specialize in the super ideals we got our name "Good Old Gold" because we have always featured a unique selection of antique and estate jewelry as well. That stone is a modern round brilliant cut that we took in when purchasing an estate. We do have a few of those laying around but we have recut 99% of the them. I keep that around for educational purposes.

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Thanks G.

 

Very few consumers I meet on the forums are able to assess the kind of information you have by just looking at the images. I'm impressed. It is virtually impossible to assess clarity/color from these images though but fyi the poop 1.01ct is an I SI2 and the .81ct is a G VS1. You'll see a link to the G VS1 but I don't think I have all the data scanned on that 1.01 so its probably not posted. I use that stone in house to demonstrate to clients *what not* to purchase (amongst other poop examples). :P

 

Appreciate the correspondence.

 

Ex/Ex

Rhino

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