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Cut Score vs PS Parameters

AlanDiamond

Rough_Rock
Joined
May 15, 2019
Messages
24
Hi All,

I've been reading this forum where PS folks mention to follow these guidelines for a good cut diamond:
54-58 table
60-62.4 depth
34-35 crown
40.6-40.8 pavillion

However it seems very hard to find a 0.90 ct SI1-VS1 diamond within this range. Sometimes depth and table match, but crown and pavilion do not. Crown and pavilion angles seem very strict given GIA rounds crown angles nearest 0.5, and pavilion angles nearest 0.2. On Bluenile I only found 1 diamond within these, which are part of their Astor cut and far out of my budget.

So I am wondering if I am approaching this diamond search the wrong way. Maybe these parameters are too strict, and only for those looking for super ideal cut. Is it necessary to be so strict, or is ideal cut already good enough for a diamond to sparkle?

I have found this diamond on PS:
0.90 ct VS1 I
table 57
depth 62.1
crown angle 36.0
pavilion angle 40.6
GIA XXX
HCA = Excellent

The crown angle would be over PS recommendation, but HCA tool gives it <2. So should I skip this stone because of the large crown angle, or is this actually a good stone I should consider?
 

OoohShiny

Ideal_Rock
Premium
Joined
Apr 25, 2014
Messages
8,228
HCA tool giving a score under 2 indicates the angles work together, which is good news. It does mean, though, that you can have a 32 crown with a 41.2 pavilion, or a 36 crown and a 40.6 pavilion (as you've found) which is outside the PS-recommended 'safe' or 'superideal' paramters but would still 'work'.

There are other considerations in terms of potential for over-obstruction in shallow-pavilion stones and overall-shallow stones, AIUI, but using the HCA tool can give you potential options from a much longer list. You should also be aware in terms of the impacts of high crowns vs low crowns, for example.

Put your desired stone parameters into the search bar at the top of the forum, and when it takes you through to the results page, it has filters and Advanced Filters you can use to input the PS-recommended parameters - you should have quite a large range to choose from.

The HCA score slider can then be moved to, ideally, Excellent, but the Very Good score can also be worth a look - you just have to be a bit more clever in picking out potential winners :)

You can click on the HCA score of a particular stone in the results list and it will take you through to the HCA results page for the stone :) (but be careful if you only have limited HCA uses per day because it will soon run out! lol)
 

ringo865

Ideal_Rock
Premium
Joined
Feb 14, 2014
Messages
2,897
Or post your budget and desired specs and let PSers point you to well-performing stones.
 

marymm

Ideal_Rock
Premium
Joined
Apr 21, 2010
Messages
5,520
OP, yes, the stone you found is a solid candidate which I recommend purchasing and examining in person to confirm that it has a lively performance in various lighting conditions (as long as there is a good return policy).
 

Kaycee2018

Brilliant_Rock
Premium
Joined
May 14, 2018
Messages
994
OP, the 1.85 ct diamond is my avatar has very similar specs to the ones you are considering (mine has 57% table, 61.9% depth, CA 36.0, PA 40.6, GIA XXX, HCA 1.7) and it performs beautifully. Granted, GIA rounding, the accuracy of the cutter and the slight differences mean they might not perform the same, but it is definitely worth considering as long as it is returnable in the event you are not happy with it. GL!
 

AlanDiamond

Rough_Rock
Joined
May 15, 2019
Messages
24
Or post your budget and desired specs and let PSers point you to well-performing stones.

Thanks, I'm looking for:

0.88 - 0.91 ct
VS2 - VS1 clarity
G-I color
Budget: $3300 - $4500
 

AlanDiamond

Rough_Rock
Joined
May 15, 2019
Messages
24
psdiamond.png

Would this be a good diamond? Not sure how bad the indented natural is, considering VVS2 and last on the list, I guess it's barely noticable to have any damaging effect?
 

lovedogs

Super_Ideal_Rock
Premium
Joined
Jul 31, 2014
Messages
18,014
psdiamond.png

Would this be a good diamond? Not sure how bad the indented natural is, considering VVS2 and last on the list, I guess it's barely noticable to have any damaging effect?

This is a good choice in terms of angles working together. VVS2 is overkill on clarity (IMHO), and I wouldn't worry about the indented natural on such a high clarity stone. I would ask for an ASET/IS to confirm performance.
 

AlanDiamond

Rough_Rock
Joined
May 15, 2019
Messages
24
This is a good choice in terms of angles working together. VVS2 is overkill on clarity (IMHO), and I wouldn't worry about the indented natural on such a high clarity stone. I would ask for an ASET/IS to confirm performance.

Found one in VS2 clarity, what do you think of this one:
https://www.bluenile.com/diamond-details/LD12316381?click_id=474935135

It's got crystals and feathers, you can see a bit of them in the video at the top of the diamond. Would this be eye clean?
 

lovedogs

Super_Ideal_Rock
Premium
Joined
Jul 31, 2014
Messages
18,014

AlanDiamond

Rough_Rock
Joined
May 15, 2019
Messages
24
almost all VS2 stones will be eye clean from a reasonable viewing distance, especially in 1ct or smaller sizes. I think this will be eye clean. Did you run it through the HCA?

Yup, first thing I did :) Is there any way to check there's no weird H&A going on, like the cheated GIA EX I first found?

I found the same diamond here which has black/white image of the diamond
https://www.adiamor.com/Diamonds/0.92-ct-G-VS2-Excellent-Cut-Round-Diamond/D43225836

Light Return:
Excellent
Fire:
Excellent
Scintillation:
Very Good
Spread:
Very Good
HCA Score :
1.3 - Excellent - within TIC range
 

lovedogs

Super_Ideal_Rock
Premium
Joined
Jul 31, 2014
Messages
18,014
Yup, first thing I did :) Is there any way to check there's no weird H&A going on, like the cheated GIA EX I first found?

I found the same diamond here which has black/white image of the diamond
https://www.adiamor.com/Diamonds/0.92-ct-G-VS2-Excellent-Cut-Round-Diamond/D43225836

Light Return:
Excellent
Fire:
Excellent
Scintillation:
Very Good
Spread:
Very Good
HCA Score :
1.3 - Excellent - within TIC range
Other than the ASET and IS images, I don't think so. But maybe the experts could chime in about it.
 
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