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Buying earings and need some advice on HCA + Clarity

S

SKR

Shiny_Rock
Joined
Oct 1, 2006
Messages
199
Hi All,

I am in the market to buy my wife diamond earrings (round) and need some advice on how to interpret an HCA score as well as what the lowest clarity level I should consider to still guarantee an eye clean diamond.

I have been offered a pair of diamonds (H colour) which give HCA scores of 2.5 and 4.4 respectively. Would this pair be mismatched in terms of performance? Should I reject both stones because they are not under a score of 2? Both are HRD certified and have been classified as excellent in terms of cut by the lab.

If I do reject them (which I am tending towards) then should I just stick to diamonds which HCA scores of 2 or lower? Would this guarantee great light performance and I dont have to worry about anything else apart from the colour, clarity and fluorescence?

Also I am trying to stick to VS2 or better diamonds - these should be totally eye clean right ?

Sorry for all the questions! All advice appreciated.

Thank you
 
Picking well cut rounds is easier than any other shape.
Two steps:
1. HCA, reject stones that score over 2.0.
2. Get Idealscope https://www.pricescope.com/tools/ideal-scope pics and compare them to this chart.
http://www.ideal-scope.com/1.using_reference_chart.asp



A good HCA score is not enough to make the final selection because the Crown and Pavilion angles used are each an average of 8 numbers.
Those numbers may all 8 be the same (preferred) or all they could be all over the place, which will be revealed by an Idealscope image.

using_IS_Reference_Chart_72.jpg
 
Are you in Europe by any chance?
 
Yes, VS2 is great clarity for earrings and some here do SI1, but it requires finding eyeclean stones. I'd stick with GIA Excellent cut and then narrow down that bunch with HCA scores 2 or less.
 
Kenny & Diamondseeker2006 - thank you for the charts and information. I am going to reject the two stones in questions because of the HCA score. One of them was close to a score of 2 (details below) but the other one was quite far off. I will also ask vendors to send me idealscope images of of any diamonds they are suggesting going forward.

HRD Antwerp
- H colour, VS1
- Measurements: 9.19 x 9.26 x 5.75
- Proportions: Excellent
- Polish: Excellent
- Symmetry: Excellent
- Girdle: Medium 3.5% faceted
- Culet: Pointed
- Depth: 62.3%
- Table: 57%
- Crown Height - 15.5% (36.0 deg)
- Pavilion Depth - 43.0% (40.8 deg)
- Length Halves Crown: 50%
- Length Halves Pavilion: 80%

The really weird thing on this diamond is that if I use the crown height and pavilion angles, I get a HCA score of 3.7. Using the percentages instead I get a score of 2.5. Thats a big difference - why is that ?

JulieN - yes I am in Europe. However I am willing to buy from the US as well as Europe.

Thank you
 
SKR|1326624432|3103333 said:
The really weird thing on this diamond is that if I use the crown height and pavilion angles, I get a HCA score of 3.7. Using the percentages instead I get a score of 2.5. Thats a big difference - why is that ?
Click to expand...

It's a math thing related to how the numbers are rounded.
According to Garry Holloway, who created the HCA, the angles are more accurate than the heights.
 
Hi,

Isn't that an awfully big diamond for earrings? A one carat, I think is only 6 and half mm. Are you really looking for diamonds in that size? Please come back and show us what you buy.

Annette
 
Whoa...you are looking at just under 3 carats each for earrings????
 
Yes both are 3.02 carats exactly each.
 
kenny|1326650492|3103479 said:
SKR|1326624432|3103333 said:
The really weird thing on this diamond is that if I use the crown height and pavilion angles, I get a HCA score of 3.7. Using the percentages instead I get a score of 2.5. Thats a big difference - why is that ?
Click to expand...

It's a math thing related to how the numbers are rounded.
According to Garry Holloway, who created the HCA, the angles are more accurate than the heights.
Click to expand...

OK Kenny thanks. Will only use the angles which makes the diamond worse in this case.
 
I am waiting for one vendor to get in touch with me but to be honest there doesnt seem to be a whole lot of well cut diamonds out there.

What do people think of getting the diamonds cut to order - does this work out more expensive ?
 
You're just not going to be able to do that with almost 3 ct. stones. Cutters are limited in the rough they can get. You'll very likely have to find stones from two different vendors. What is the smallest size you would consider? This would be far easier if you were doing 2 cts. per ear.
 
SKR|1326656924|3103550 said:
I am waiting for one vendor to get in touch with me but to be honest there doesnt seem to be a whole lot of well cut diamonds out there.

What do people think of getting the diamonds cut to order - does this work out more expensive ?
Click to expand...

Very true, and there is a very good business reason for this.
Cutting for good light performance means cutting away more weight.
Cutting for good light performance means throwing away weight and having to find that very small segment of the buying public who understand good cut and understand that they have to pay for all that "wasted" rough.
A piece of rough could be cut to either 1.01 ct with poor light performance or 0.70 ct with good light performance.
Few buyers know about good cut but almost every buyer wants a larger diamond.

Sure you can buy a larger cut diamond and have it polished into a better cut by someone like Brian Gavin at briangavindiamonds.com.
You may want to give him a call and discuss this with him.
Note that when submitting a diamond for recutting YOU assume 100% of the risk.
If it explodes on the cutting wheel the cutter is not liable.
You lose all your money.
This is why I'd talk to Brian BEFORE buying anything for recutting.
He can help you avoid higher-risk stones.
 
Lowest is 3 carats each. Dont want to go smaller - she already has smaller ones. 3 carat just seemed like a good mark over what she already has.
 
Way out of my budget unfortunately. I am looking at about and I colour in the VS1 or VS2 range.
 
SKR|1326659776|3103587 said:
Way out of my budget unfortunately. I am looking at about and I colour in the VS1 or VS2 range.
Click to expand...

Sorry...posted the other H pair before seeing this.
 
Thank you diamondseeker - thats more like it! I wonder why the second diamond is so much cheaper with pretty much identical specs. Will contact the vendor tomorrow - I cant get all the measurements required for the HCA calculation from the GIA reports - I think they might be missing a page?
 
You are welcome! The measurements are there. You have to click the GIA report and the copy of the report comes up. Measurements are on the stone drawing.

You will see variation in prices. Some may be less because the supplier has had the diamond longer and wants to move it and that kind of thing. Oh, and the second stone has very good for polish (which doesn't matter..you can't see the difference).
 
I ran them through the HCA for you but I knew from the measurements that they would score well. :))

.8 excellent for one and 1.0 excellent for the other.
 
Tried that and the second page wasnt coming up at all on my apple pc. Tried with windows and its fine.

Both are coming up with a score of around 1.0. Am going to look into them further.

:appl:
 
Great! Good luck and PLEASE post pictures for us of whatever stones you end up with! We'd love to see them! :love:
 
I did a search a few years ago with help from people on this forum and ended up with a perfect oval stone. It still gets great comments every time she wears it !

Everyone is fantastically helpful on this site.

Thank you diamondseeker and and Kenny.
 
You are so very welcone! I am just glad I came here myself before buying some diamonds a few years ago!

When you take pictures of the studs, we'd love to see the oval, too! :))
 
Oh, my!!! That is an incredibly stunning ring!!! :love: :love: :love: I truly love how you set it!
 
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