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eliminate numerical output from HCA?

slg47

Ideal_Rock
Joined
Apr 4, 2010
Messages
9,667
Would the HCA be used more effectively if the results were only Excellent/Very Good/Good/Fair instead of having the numerical result? I do not mean to criticize the HCA-I think it is very useful! but I see a lot of posters confused with the numbers and thinking that 1.0 is better than 1.9, etc. If these were all classified as 'excellent' would this help with using the HCA as a weeding tool?
 

Christina...

Ideal_Rock
Joined
Mar 7, 2011
Messages
5,028
I agree, and not to be critical either, but it may be easier to understand if the graphing of the results were more clear. For instance I've seen people post that they received a 1.4 HCA but when I enter the data it falls within the great for a pendant or earring category.

There was a discussion on another thread about starting a sticky for newbies and including information on how to use the tools that PS offers, how to evaluate cut, the differences between labs etc....in fact it may have been you that was involved in the coversation :?: I agree with you and think that it would be great to include some additional information about how to use the HCA correctly.
 

slg47

Ideal_Rock
Joined
Apr 4, 2010
Messages
9,667
Christina...|1334939579|3176250 said:
I agree, and not to be critical either, but it may be easier to understand if the graphing of the results were more clear. For instance I've seen people post that they received a 1.4 HCA but when I enter the data it falls within the great for a pendant or earring category.

There was a discussion on another thread about starting a sticky for newbies and including information on how to use the tools that PS offers, how to evaluate cut, the differences between labs etc....in fact it may have been you that was involved in the coversation :?: I agree with you and think that it would be great to include some additional information about how to use the HCA correctly.

Christina I was involved in the conversation...I think most of the info is under the knowledge tab.

I am bumping this...curious to hear other thoughts/opinions...
 

catalyst

Rough_Rock
Joined
Mar 25, 2012
Messages
17
Slightly off topic but still related. Something that should be added to the knowledge base up there for newbies like me is the fact that GIA cut graded is a bit lenient under the standards of PSers. I didn't read anything saying Ex/Ex/Ex sometimes wasn't enough until after we had made the decision (not that its definitely to late, or that we definitely even think they are not perfect)

I had every intention of buying online, however when we found a B+M with the perfect setting and the pricing was good I was pretty happy. However it has turned out that the stones we have picked are classified as steep/deep by the people here. I've got an open mind going in to pick them up when they call, and will say something if we are not happy.

Its the one piece of information that didn't come up until you started reading threads by typing in steep/deep or GIA Ex/Ex/Ex, low HCA. I had no idea I should be running the HCA on stones that had already been graded highly. Now that I know what to look for, I will use it to my advantage. Once again cheers for all the info guys, its nice to be an informed shopper in a field I knew nothing about a month ago.
 

yssie

Super_Ideal_Rock
Premium
Joined
Aug 14, 2009
Messages
27,242
I missed the discussion... sounds like a good topic.


catalyst Your stones are not steep/deep by any definition of that term, which has no official or consistent definition anyway (the same reason you won't ever see it in a dictionary or glossary or anything like that).

The variance within GIA Ex is well-documented - see John Pollard's excellent article below for one example - and honestly, I think it's right where it should be: available to those who want to do a bit more digging, but not front and centre of the PS landing page where it will just scare new consumers into doggedly pursuing some arbitrary and misguided venn-diagram of cheat-sheet gospel
https://www.pricescope.com/journal/laboratory_cut_grades_what_report_doesn%E2%80%99t_show


I don't like the idea of eliminating numerical output because I think that puts even more emphasis on the pass/fail cutoff. I think it's easier for a new consumer to understand that 2 might be the cutoff for an official "pass" but 2.5 is pretty darn close, definitely "probably worth investigating further", vs. just a blanket "it failed", y'know? Unless I'm misreading your intent slg! Would you keep the pass/fail qualification?

I would like to see the descriptions - fire/scintillation/etc. eliminated, we've seen people worry about those blurbs and an accurate prediction requires more inputs anyway - those are nuances that are hugely affected by proportions other than the Big Four.
 

catalyst

Rough_Rock
Joined
Mar 25, 2012
Messages
17
Thanks for the reassurance Yssie :),

As a new consumer I can see both sides of this argument.

Firstly, even 5 minutes of reading will make anyone aware (even us uneducated ones) that the HCA is a rejection tool only and once the score is below 2 they are worth further investigation with images. To the people who still ask whether a 0.8 is better than a 1.5, this could be made more clear on the page where they input the numbers?

However from my reading further and further into the forum, the HCA is sold as a pass(based on further investigation)/fail tool. I haven't seen many topics where a stone scores 2.4 and everyone says thats close to 2, you should have a further look.

Also most regulars on this site I assume are people who don't very often by from a B+M, and so perfection is something to strive for with all the tools at your disposal when you can't see the stone (I know everyone is going for perfection in the long run, some people just know more than others)

I don't see the number scoring as broken at all, its only once people go searching on their result that says "buy if the price is good" that it doesn't always quantify how much of a real world "loss" you are making to "save" this money.

Online buying totally changes all I have said above, with, I agree, the only safe advice to give being to achieve perfection.
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
18,423
slg47|1334939134|3176245 said:
Would the HCA be used more effectively if the results were only Excellent/Very Good/Good/Fair instead of having the numerical result? I do not mean to criticize the HCA-I think it is very useful! but I see a lot of posters confused with the numbers and thinking that 1.0 is better than 1.9, etc. If these were all classified as 'excellent' would this help with using the HCA as a weeding tool?

Take a situation where a stone is close to the optimum border for several factors and you get a higher scroe. There are also unshown factors like the computation behind the scenes for girdle thickness (sepecially if its likel to be too thin) and associated penalties that show up in the final raw number.
here is a link to some workings and reasoning:
http://www.diamond-cut.com.au/15_summary.htm
 
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