HCA vs CUT

[ame]

Ame, you have been very helpful to many who need diamond buying advice. My post was not directed to anything you said in this thread or any thread. I was merely stating my opinion per my standard.

Among all C's, cut is the most important to me, and whenever I need to skim to meet my budget, I have never compromised my strong desire for best cut diamonds. Therefore, I stay away from anything that has less than a GIA excellent or AGS ideal symmetry round diamonds. I rely heavily on HCA to SCREEN my diamonds before requesting to view diamonds in person. Understanding that HCA is based on an average of a few measurements, I do not want to risk the trouble of paying shipping (can cost up to $200) just to view the diamonds in person in order to confirm their acceptabilty. Yes, I may miss some great looking diamonds that do not meet my excellent/ideal symmetry requirement, but I accept this possibility to err for the safe/sure side. Likewise, I do not mind missing out on this diamond if it turns out to be OK. So if it gives me savings, but I do not mind paying more money. You see, I buy nothing but the premium best cut, ACA diamonds, so I would not mind paying more money. I would rather get the savings from opting with a lower color, lower clarity (but still eye-clean), smaller carat size or even increased budget.

Back to OP, let me repeat, personally, I would continue to look for the best cut diamonds. There are plenty of fish around. Besides, you may not want to trouble yourself with more work/cost associated with pursuing your two diamonds further.

Right, and you're entitled to your opinion. I am posting based on education and experience and facts, not just my standard based on just anecdotal evidence. The OP might prefer the size she's selected, the clarity and the color combination shown. Those might not be up for consideration, and I am being respectful of that regardless of what I might choose differently. She came on here asking about cut vs HCA score, and I have explained why cut and proportions ***** the HCA. Not to tell her why she needs to patronize my favorite jeweler and their brand of stones.

From what I just read, you are telling this poster that because YOU think Whiteflash's brand of diamonds are the best, because YOU like yours, that she should eliminate any other possible contenders because they're NOT from Whiteflash. Because these stones might not be ACAs therefore they should automatically stricken from her contention? Your opinion is not fact. You're pushing your standards onto someone else simply based on your experiences with Whiteflash that other people might not share or agree with. The stones this poster has been considering are definitely high quality stones, and that first one would probably be on par, if not better than the ACAs you hold so dear because it literally has the correct angles and proportions to produce excellent light return and fire. You are choosing to believe that ACAs are better than anything, and saying so is not a factual assessment, that's your opinion not based on anything more than anecdotal evidence.

ACAs are fine, but not the best there ever was. I've seen and owned them, I don't get the hype. And with Brian Gavin no longer handling their cutting, they probably won't ever be as consistent as they were when he was there. I do think they cut stones well--not as well as before he departed--but they're not THE BEST or THE STANDARD. I know most people on Pricescope feel that way, but it's not fact. Just like some people believe that if it's not from Tiffany's it's unworthy. Or from Cartier. Or whatever. That's not fact, it's opinion. You are entitled to feel that way, but don't declare that as fact.



...



Also, some people don't care for the H&A pattern often found in "superideals" either, I happen to be one of those people. I don't wear a standard RB superideal, I wear a modified superideal. But if I DID want an RB H&A cut, I would probably get myself an Infinity. That is a brand that I would rank above all because they are consistently cut to actual super ideal standards.


ETA: I am also not trying to be obnoxious, so I apologize if it sounds that way. I am trying to make sure that opinions are not clouding fact for this poster. Or any poster that reads this.

 

[Yokochic]

Appreciate everyone's opinion on this

My main reason for starting this thread is to understand & learn more about how to choose a good diamond before making up my mind as to which one to purchase.

I know cut is definitely most important. As been pointed out by Ame a number of times, the table & and depth percentage are important, will keep those numbers in mind.

Thank you for everyone's contribution, esp Ame for your informative expertise Really appreciate your help.

I do agree that VVS1 or VVS2 are both "too good", I will try to look for lower clarity which will cost less.

 

[lilmountaingirl]

lilmountaingirl- May i know what features / proportions you are attracted to?

[/QUOTE]

Well to me a round diamond should have excellent symmetry. I think it is as important as excellent cut. I think very good polish is ok but not very good symm. Also, i like my rounds to look plump like Little Miss Muffet's pillow, but not deep. Lol. A sort of cushion appeal without the depth. So i prefer a table in the outer excellent range and the depth also right at the outer excellent range. I also prefer medium, medium to slightly thick, or medium to thick girdles. To me, these features give that perfect side profile IMO. If you want VVS you should get VVS. I am a clarity girl so that is really important to me. I would choose a smaller stone with higher clarity because it makes me happy. A lot of people love the HCA and rely on it heavily. I personally do not. I have read a lot of articles and it definitely has its flaws. I am a big scintillation girl too. A diamond to me is most beautiful indoors and in halogen if it has a lot of scintillation. The HCA is not as good at calculating scintillation as it is calculating fire. Also it gives completely different reads based on angles and degrees. To me that is a flawed system. If it is a great tool it should calculate both readings accurately and if you use both angles and degrees, they should have the same output. I still believe the experts at GIA know a beautiful stone whether it has beauty in fire, scintillation or proportion. A lot of people use HCA to find amazing stones. It is also a good tool to help save some money. You can find lesser rated stones with great scores. So like others say it might be a good starting place. But i would never rule out a GIA ex/ex/ex stone based on the HCA. The GIA grades are more important to me.

 

[ame]

Appreciate everyone's opinion on this

My main reason for starting this thread is to understand & learn more about how to choose a good diamond before making up my mind as to which one to purchase.

I know cut is definitely most important. As been pointed out by Ame a number of times, the table & and depth percentage are important, will keep those numbers in mind.

Thank you for everyone's contribution, esp Ame for your informative expertise Really appreciate your help.

I do agree that VVS1 or VVS2 are both "too good", I will try to look for lower clarity which will cost less.

It's my pleasure!

If you are looking online, and are willing to share budget, we can help you look. I think a VS1 would be ideal, because it's still mind clean enough and will also be absolutley eye clean. If you put a VS1 next to a VVS1 that were identically cut and colored, you really would not be able to see the difference.

 

[lilmountaingirl]

If you put a VS1 next to a VVS1 that were identically cut and colored, you really would not be able to see the difference.

Definitely true! I am not really able to decipher a clarity difference until I hit SI1. At this clarity i start to notice a greyish tint. Can't see any inclusions but see a tint produced by them.

 

[ame]

That is probably based on the type of inclusion. A cloud or even a couple dark crystals can reflect all over causing a grayish tone. It's also possible that it's not even clarity, that the diamond itself is in fact slightly grayish.

 

[lilmountaingirl]

That is probably based on the type of inclusion. A cloud or even a couple dark crystals can reflect all over causing a grayish tone. It's also possible that it's not even clarity, that the diamond itself is in fact slightly grayish.

I think i remember you telling me that before actually, about diamonds facing up different colors. Grey must be a color i am very sensitive too. Interesting! I think i have been associating it with clarity but maybe it is a combo of the two. I can't stand a grey diamond. I love yellow, brown, not grey. My favorites are either really white or with a yellow tint but I am most attracted to low colored diamonds, K-M. Lol. I would pay a premium for a yellow M with an IF clarity. I know i have unconventional taste and am weird about wanting IF diamonds... At least i know and accept that. Lol.

 

[ame]

Nothin' wrong with that at all! It's important that people get what they want and not settle. But as long as you make an educated choice, that's what matters.

I think my sweet spot for color is around a G-J. I of course would LOVE a D with SBF

 

[Yokochic]

Hi all, in a dilemma again. Looking at another one here.

1.20 carat G VS2. Excellent/very good/Excellent. Total depth percentage 61.1%, table size percentage 59%, crown height precentage 14.3%, crown angle 34.1 degrees, star length percentage 50%, pavilion depth percentage 43.3%, pavilion angle 40.9 degrees, lower half length percentage 75%, medium to slightly thick girdle, faceted girdle finish, cutlet none.

1.07 carat G VS1. Excellent/Excellent/Excellent. Total depth percentage 61.5%, table size percentage 57%, crown height precentage 15.1%, crown angle 35.2 degrees, star length percentage 50%, pavilion depth percentage 42.8%, pavilion angle 40.7 degrees, lower half length percentage 80%, medium girdle, faceted girdle finish, cutlet none.

I think from the HCA score the 2nd one will be better but obviously the first one is bigger.

Which would you pick?

Thanks

 

[cung]

The most important factor to get a beautiful diamond is the cut quality. That's all in the proportions and angles. Unless it's an AGS cert which truly does officially and effectively grade cut, which it doesn't sound like it is based on using Excellent as the cut quality, I go based on numbers and not what they call Excellent because GIA has a pretty wide margin for what they consider Excellent and I have seen some serious dogs that get called Excellent, and some amazing ones they only call Very Good. Excellent Symmetry is obviously great, but you really want the proportions to be right because the angles are where the cut quality really lies.

In diamond #1 every one of those numbers is truly ideal. A "true ideal" would be around a 55% table, and around a 61% depth with the 34ish crown angle and 40.7ish crown angle. These are like magic numbers.

A 57% table does still fall under "ideal" but it changes the crown angle just enough (in this case into the 35 degree area) sometimes that you lose a little fire return and get more white light return than if you have a 55% table. A bigger table changes the look overall, and changes the fire return vs the white light return. A smaller table gives more color light, a larger one more white light. Some people don't mind that change. Me personally, I like the smaller table.

Another reason I selected 1 over 2 is the girdle, that diamond is "thicker in the middle" meaning more of it's weight is in the middle and it will not face up as large as one with a thin or thin to medium girdle, which is preferred. So it's smaller in diameter than it "should be" vs. the first one. Not by a lot, but it could make the difference.

Not sure who the seller is, but I would seriously ask for an ASET and or IdealScope image and photos if at all possible. I assume you're outside of the US, and working with a vendor IN the US. I know Blue Nile doesn't do that, but there are many online vendors that will.

As far as HCA goes, that is really only a tool to help start weeding out stones that would have angles that would in theory produce a less beautiful stone. Its a PS/Garry Holloway thing, not developed by AGS/GIA or any other lab. But it has its uses in selecting a stone based strictly on paper, and not on visual. The best tool for selection is the eyes!

tks a lot I found this threat. It's so helpful and answer a lot question I do not have a chance to ask, or do not know what I should ask for lots of information. Will spend more time searching for my stone based on your advice.
Tks again for open this and to great responses here.

 

[ame]

Hi all, in a dilemma again. Looking at another one here.

1.20 carat G VS2. Excellent/very good/Excellent. Total depth percentage 61.1%, table size percentage 59%, crown height precentage 14.3%, crown angle 34.1 degrees, star length percentage 50%, pavilion depth percentage 43.3%, pavilion angle 40.9 degrees, lower half length percentage 75%, medium to slightly thick girdle, faceted girdle finish, cutlet none.

1.07 carat G VS1. Excellent/Excellent/Excellent. Total depth percentage 61.5%, table size percentage 57%, crown height precentage 15.1%, crown angle 35.2 degrees, star length percentage 50%, pavilion depth percentage 42.8%, pavilion angle 40.7 degrees, lower half length percentage 80%, medium girdle, faceted girdle finish, cutlet none.

I think from the HCA score the 2nd one will be better but obviously the first one is bigger.

Which would you pick?

Thanks

Neither personally, but if it was JUST these two, the 2nd. The numbers on the first immediately remove it from contention, size or not. There's no way I'd be involved with a stone with a 59% table, ever.

 

[Yokochic]

Neither personally, but if it was JUST these two, the 2nd. The numbers on the first immediately remove it from contention, size or not. There's no way I'd be involved with a stone with a 59% table, ever.

Hi ame, thanks for the info. Didn't realise it will be that bad ....

Is the 2nd one acceptable at all? Or do you think the lighting will be very bad?

Thanks

 

[ame]

The 2nd one still falls under ideal. That's one I'd want more pics and data on. But the first one I struck immediately.

Ideally you want around a 55% table, but 57% still falls under ideal.

 

[Yokochic]

The 2nd one still falls under ideal. That's one I'd want more pics and data on. But the first one I struck immediately.

Ideally you want around a 55% table, but 57% still falls under ideal.

Got it! You are such an expert

 

[aliwylie]

Hello guys,

I am wondering if you would be kind enough to give an opinion on which of the 2 diamonds below you think are better. I appreciate without more information you cant say for sure but I want appreciate an off-the-cuff opinion anyway. The 2 diamonds are as follows:

1. 0.51ct, Table 56, Depth 62, Pav 40.6 crown 35.5 girdle 3.5% medium
2. 0.63ct, Table 56, Depth 62.1, Pav 40.6 crown 35 girdle 4% medium-slightly thick.

1 has HCA score of 1.4
2. has HCA score of 0.9

Both D IF triple excellent.

PS I know a bigger carat is worth more but this is reflected in the price. If anything my fiance does not want a big diamond as she has small thin fingers.

I am wondering how accurate the HCA scores are considering they are based on a girdle of 1.5% whereas both that I am looking at are greater than 3%. Can you offer any advice on this please? I would really appreciate it if you can get back to me as soon as possible.

Many thanks,

Ali