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Query about non-perfectly round diamonds

dk168

Ideal_Rock
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Hi peeps,

I do not know much about diamonds except what I like in 4Cs and shapes, and would like some advice please. More out of curious than anything else.

I measured my mum's near 1.9ct MRB, took many measurements using a pair of calipers, and found a difference of 0.11mm between its narrowest and widest points, 7.96 to 8.07mm respectively.

I checked the MRBs available for sale using PS search tool, and discovered not all round diamonds are perfectly round.

Considering this stone is over 40yo, I am not bother if it not being perfectly round, as it is round enough to my naked eyes.

Just wondering what is the acceptable tolerance between the smallest and largest measurements for a stone to be considered as a round please.

The depth is 4.89mm in case anyone is interested.

TIA.

DK :))
 
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dk168

Ideal_Rock
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Couple pics of the stone itself, definitely not H&A, and it has an extra facet in the girdle. However it is very sparkly to me, and has sentimental value.

It will be set in an open bangle, bezel set with no millgrain in platinum, and I shall wear it as often as I can.

20200224_212310.jpg
20200224_212259.jpg

DK :))
 

Karl_K

Ideal_Rock
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Was it chipped and repaired?
 

AV_

Ideal_Rock
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Blue Nile displays the L/W ratio for rounds, there are many 1% off-round & I have not looked further.

2p


Digressing,
the stone seems to have very long lgf that were recently argued as a good choice for some proportions... It makes me curious.
 

dk168

Ideal_Rock
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Was it chipped and repaired?
Not chipped or repaired as far as I am aware. It has never been worn, however, it had been set twice.

DK :))
 

dk168

Ideal_Rock
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Blue Nile displays the L/W ratio for rounds, there are many 1% off-round & I have not looked further.

2p


Digressing,
the stone seems to have very long lgf that were recently argued as a good choice for some proportions... It makes me curious.
That's useful to know, thanks!

DK :))
 
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sledge

Ideal_Rock
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This is something I noticed early on when I started learning about diamonds.

The vast majority aren't perfectly round, at least according to the measurements on the lab reports. It seems pretty normal to have variance in the L and W measurements up to 0.07mm or thereabouts.

I've noticed it in GIA or AGS stones and super ideal stones as well.

Not sure if the small variances are truly off by a hair, or if the devices measuring them have tiny variances in calibration that rarely kicks back perfect dimensions. Either way, it seems to have negligible effects from what I can tell, if any.

I have seen some newer stones be off by 0.10mm or so, but it seems less common.

From a mind clean perspective I dislike that much variance. But I seem to recall @Johnbt's wife having a WF stone with that sort of variance and it doesn't seem to hurt performance in the least.
 

dk168

Ideal_Rock
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I did some more random checks on new ideal cut round diamond dimensions, and a lot of them show a small amount of variations around 0.05mm.

I am satisfied that a small variation is the norm.

DK :))
 

cflutist

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This is something I noticed early on when I started learning about diamonds.

The vast majority aren't perfectly round, at least according to the measurements on the lab reports. It seems pretty normal to have variance in the L and W measurements up to 0.07mm or thereabouts.

I've noticed it in GIA or AGS stones and super ideal stones as well.

Not sure if the small variances are truly off by a hair, or if the devices measuring them have tiny variances in calibration that rarely kicks back perfect dimensions. Either way, it seems to have negligible effects from what I can tell, if any.

I have seen some newer stones be off by 0.10mm or so, but it seems less common.

From a mind clean perspective I dislike that much variance. But I seem to recall @Johnbt's wife having a WF stone with that sort of variance and it doesn't seem to hurt performance in the least.
20200224_162734.jpg

Hmmm, looks like my worst CBIs are off by .03mm. That sounds funny doesn't it, lol

Best is off by .01mm but I am very happy that my two side stones on my 3-stone are off by .01mm and have the same CA and PA.
 
Last edited:

Johnbt

Shiny_Rock
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We're looking at thousandths of an inch.

.03 mm = .001181102 in.

fwiw

.09 mm = .003543307 in.
 

dk168

Ideal_Rock
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We're looking at thousandths of an inch.

.03 mm = .001181102 in.

fwiw

.09 mm = .003543307 in.
I get that, however, a variation exists, regardless how small.

DK :))
 

Johnbt

Shiny_Rock
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Variation certainly exists if you use enough decimal places when you measure and don't round to two places. Sort oflike a flawless diamond isn't flawless if you use enough additional magnification.
 

sledge

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Her diamond still appears to be round. :)

7.35 x 7.44 x 4.55 mm 1.51 ct

www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-3955177.htm
Thank you for confirming, and sharing. Always enjoy seeing some nice eye candy. Proportions are amazing and the video is even better.


20200224_162734.jpg

Hmmm, looks like my worst CBIs are off by .03mm. That sounds funny doesn't it, lol

Best is off by .01mm but I am very happy that my two side stones on my 3-stone are off by .01mm and have the same CA and PA.
This does not surprise me in the least. Your stones are amazing. Of course, you also know I'm sweet on the 2.18. :love:


Variation certainly exists if you use enough decimal places when you measure and don't round to two places. Sort oflike a flawless diamond isn't flawless if you use enough additional magnification.
IMO, you and @dk168 are both right. A variation does exist, but as you have pointed out it's a rather meaningless number in the big scheme of life. Our eyes can't detect that tiny of a difference, and it's possible just tolerances in manufacturing equipment account for these "differences" we see in the measurements.

Obviously, as the variation creeps up higher and higher it becomes more meaningful. Most people can detect 0.20mm difference in a side by side comparison. Some people can detect 0.10mm, but not everyone. Just depends on their visual acuity.

FWIW, my wife's stone has 0.03mm variation and I can't detect it with the naked eye. I purchased from BGD in 2018 and it measures out at 6.18 x 6.21.
 
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