Alternative to Portable HCA

[kev-man]

I''ve been searching a little on having a portable HCA. Here is a different idea that I think would work but please correct me if I''m wrong.

It seems that the HCA chart is based off of Table size. I changed the depths of stones for different tables (57 table with 57.5 depth vs. 62 depth as well as 61 table with varying depths) and it didn''t seem to change the chart too much (or possibly at all).

From here then the only other variables you are required to enter are Pavilion and Crown angles (assuming no culet) which seems to simply move the x mark across the x/y axis.

So couldn''t you just make about 5 color printouts and take them with you to the store (table size of 56-61 for example) and then see what color zone the stone you are looking at falls into? This of course wouldn''t get you a number rating but it seems that red would be under 1, orange under 2, and yellow under 3 etc. You can also make sure that the stone doesn''t fall into a green or blue zone (assuming you want to make sure has a lower rating). Also if the table is not a round number you could probably use two printouts to get the idea (for 58.5 table you would look at both 58 and 59 table charts).

I am far from an expert here and was just playing with the HCA but I would think this should help out when you are in the store (you can also print out some descriptions of what the HCA is when the sales person tries to explain that you are reading something that is nonsense, no offense Garry, you know how salespeople are).

Anyway if one of the experts around here or perhaps Garry can shed light if this would work reasonably well to walk in to a store armed with the HCA at your disposal.

Thanks.

 

[Regular Guy]

1) I think Garry WILL be interested in your comments.

2) This is one of the more creative things I''ve heard about this...not sure the extent it is right or not, though.

3) One supplement to your idea; consider just getting buy in from your vendor on the use of the HCA, especially if it''s true. If it''s a requirement for your purchase, have them bring up a browser with you, and use it live for any options you''d like to consider more seriously.

 

[Garry H (Cut Nut)]

If you are going to a store then why take a rejection tool when for a very small outlay you can take aselection tool? An ideal-scope.

I do not use HCA when I am where the diamonds are.

 

[kev-man]

I agree that an ideal scope would be better to use, but many of us are beginners and only purchase diamonds very rarely. If I was at a store or diamond broker's office, I wouldn't be as comfortable relying on my own observations with an ideal scope as the only way to select or reject a stone.

For beginners what makes us comfortable with a purchase is reinforcement that we are making the correct decision, or at least assurances that we aren't making the wrong one. The HCA is very helpful for this purpose. I agree it shouldn't be used instead of the ideal scope but rather in addition to it (it would also be neat to see a stone with both the ideal scope and the HCA results in person right next to each other).

Also in response to the comments about using the HCA before you get to the store, while it certainly is true in theory it doesn't work quite so well in practice. Anybody who has been to a B&M store has seen the salesperson's technique of having you look at 4 stones but before you make your decision he "just remembered" that he has this other stone that is just a little bigger and nicer but seems to be "perfect" for what you are looking for. This is the time when the HCA numbers would come in very handy so you can tell if this new "perfect stone" is not so perfect at all.

Thanks again.

 

[strmrdr]

You mean not everyone can do the hca in their head?
LOL
For mainstream ideal cut combos I don't bother anymore because its easy too tell if they are under 2.
Table 55-57 - check
pavilion 40.6 to 40.9 or 41 with shallowish crowns or 40.5-40.4 with steep crowns.. check
crown is between 34 and 35 with 40.6 to 40.9 .. check
crown with 41 is under 34.5ish.. check <-- one area where the hca is too harsh at times.
40.5-40.4 with crowns around 35.5ish+ degrees .. check
add a couple exceptions: 34.5/40.5 and tight and symmetrical, long lgf%, 40.3 with 36+ and longer lgf%(short lgf and your in oec territory which is awesome too but a different kettle of fish),35/41 combo if tight and longer lgf%.
reasonable girdle .. check
reasonable depth .. check
Done

 

[strmrdr]

further want a kicken 60% table stone...
40.9 to 41 pavilion
33.5 to 34 crown.
med girdle.

33.5/41 60%t is a larger tabled tolk overall performance wise with a different look.

 

[kev-man]

Strmrdr,

That seems to be exactly my point. It seems that the HCA is useful enough for passing a first test. You have seemed to memorize exact measurements that go with different Table sizes. You could of course write down what you said, but wouldn''t it be even easier to print out the charts for cross reference. It also gives more credibility to what you are checking rather than having some numbers on a piece of paper.

The good news is that it does seem that my logic of printing out a few charts and taking them with you to the store is sound. I haven''t heard anyone yet say that it won''t work. For this reason I certainly don''t see any reason to needing the HCA on a PDA. Of course with the iPhone and other smart phones I guess people can whip out the numbers on the spot anyway.

Even still though I see a lot of value to having a large sheet of paper that points out the best range and obvious flaws of certain stones. In the heat of the moment under the stores lights it is very easy to forget much of this knowledge and get caught in the moment.

And the ideal-scope still leaves a lot of responsibility in the beginner''s hands.

 

[oldminer]

Here is the ultimate HCA< The Human Cut Advisor.

Like Garry says, you use the HCA for screening diamonds you can;'t directly see, For diamonds you can actually see, you use your sensory system, realizing that these HCA units have their own unique limitations. Combining the eyes with the various screening and measuring tools to hone your selection process is just about a perfect way to get a great stone.

 

[kev-man]

Once again (as often seems to happen on these threads), it is the experts opinions that there is a better way than to rely on the calculations.

I've been reading over many of the threads about the IS and how certain scans seem to be misaligned or light is blocked or some other thing or else that a different scan looks better. When I look at the picture I really can't tell much of a difference. Oldminer seems to be saying that nothing will beat your eyes to make the decision but my guess is that he spends a lot of time looking at stones and comparing the differences.

The casual user who goes into a store will look at stones and compare them without really knowing what to look for or how to tell the difference from one to another which only becomes harder when the lighting is cranked up. Yes they can bring an ideal scope with them, but as seems to be proven time and again you need to be trained to use it correctly and even still mistakes can be made.

Having an HCA number to confirm or deny what the customer is already seeing can not be beat. There is no downside. Yes the system has limitations but what system doesn't? I'm not saying that you should go to the store and if a stone rates well on the HCA you should buy it and ignore everything else, but why shouldn't you know the rating? How does it hurt?

The information on this site is invaluable but it is also interesting that all the novices seem to agree that having access to the ratings when making the buying decision would be very helpful. The experts are the ones saying that you don't need it and there are better ways but aren't recognizing that the novices are more comfortable also having a tangible system that doesn't rely on their own judgment.

Please don't take this topic the wrong way. I am incredibly grateful to all the information on this site and all the experts who have passed their knowledge down to the rest of us.

Thanks.

 

[Garry H (Cut Nut)]

Date: 10/18/2007 3:29:20 PM
Author: kev-man
Strmrdr,


Even still though I see a lot of value to having a large sheet of paper that points out the best range and obvious flaws of certain stones. In the heat of the moment under the stores lights it is very easy to forget much of this knowledge and get caught in the moment.

And the ideal-scope still leaves a lot of responsibility in the beginner''s hands.

You are over reliant on HCA.
For instance you would not have the ability to detect a heavily painted diamond like this one Rhino used in a study that is not a great performer. http://goodoldgold.com/4Cs/NewCutGrading/GIAExAGSIdeal/
But you would now easily notice that the ideal-scope image of that stone looks wierd. It looks different to all the other idealscope images you are used to seeing. (the one on the right - the AGS stone).

But HCA would tell you to buy it.

HCA is not a buying tool, it is a rejection tool.

 

[Quash]

As a newbie, I actually have to agree with kev-man. We simply don''t have the skill set, knowledge and training to tell the difference in quality between many diamonds with our eyes. So, we''re not looking for purchasing tools, but rejection tools, just to help us narrow down our choices when at a B&M. We want those tools to be based on the training and expertise of the people who developed them, as we don''t have our own knowledge-base to rely on. The eyes are invaluable, as Dave notes, but they can also deceive, as he demonstrated in another thread. Remember: even if we''re shown pictures, idealscopes, etc, we often still need an expert to direct us toward areas of concern or strength.

If I could open my cell phone browser and pull up a mobile version of Garry''s HCA and Dave Atlas'' Cut Grading Tool (http://www.gemappraisers.com/oldcutgrade.asp) and put in some numbers in a store, that wouldn''t help me choose a stone, but it would help me quickly eliminate stones based on an expert''s knowledge of what makes a good diamond, not simply my eyes and an experienced salesman who can see I''m limited in my knowledge.

So, what about mobile versions of these two tools? It''s probably a matter of setting up the same fields on a page without without other information and doing the same for the results, so it renders properly in a mobile browser. And include a warning for the HCA that it''s an elimination tool, of course. Would be an interesting experiment to try to create mobile versions of these tools, if nothing else.

Talk about putting knowledge in to the hands of consumers when they''re shopping!

 

[oldminer]

There is a free, zipped version of the automated AGA Cut Class grader and shape selector which can be downloaded from the gemappraisers.com website. If you have the right interface, it readily is portable. Surely, it works on a laptop, but it might work on a more compact format device. I have never tested that aspect. The HCA is also available as a download, I believe.

 

[kev-man]

Actually there seems to be very good news and this thread has been very helpful. The arguments against seem more about using the HCA in the store rather than if the printouts are a viable solution to having a portable HCA. As long as we are comfortable in using the HCA (which I have already decided I am), simply print out the charts and take them with you to the store. You now have your very own portable HCA.

Thanks again.

 

[Regular Guy]

Hey Kev,

If you draw waves on a big poster, and move it around, it will kinda be like the ocean, too.

It''s OK to make an affirmative statement in the absence of dis-confirming comment...but it is better to have confirming comment, first.

Actully, to Garry...since he''s contemplating these things...(no, nothing downloadable yet, I don''t think)...I''d say go for the upgraded, more data rich desktop version...if you''ll offer a fee based something...

 

[kev-man]

That is probably the worst analogy I''ve ever heard.

While it hasn''t been confirmed, through my research and the lack of it being refuted I am confident with my conclusions. I will wait for an expert to refute it. Until then I''m happy moving forward with what I''ve seen.

"If it walks and talks like a duck, it''s probably a duck"

 

[Regular Guy]

Consider researching Lostdog here.

Date: 10/19/2007 12:35:11 PM
Author: kev-man
That is probably the worst analogy I''ve ever heard.

You haven''t been around that long...I must have had worse...