HCA bash on diamond talk~~

[gimme]

Hi all:

recent lurker who loves this site! I''ve learned so much here and really think it''s great how you regulars help unsuspecting folks like me

Anyway, saw this on the top banner of diamondtalk today and couldn''t help but post...I''ve used the HCA myself and it seems most here think it''s a helpful tool (along with idealscopes, etc) to weed out the losers.

Just makes me wonder how controversial this system is with those in the diamond industry?
Does it really work??

http://www.diamondtalk.com/forums/forumdisplay.php?forumid=1


http://www.diamondbrokersoffl.com/why-the-hca-does-not-work.htm

 

[noobie]

Hi gimme and welcome,




I'm not too proud to say I unknowingly asked a similar question a few months ago when I first came across this site and opened up a can of worms. I also wondered why all the criticism. Let me just say that there is some history and that I'm glad that the PS's can have such a positive and helpful community as you noted.




This place focuses on open discussion and promoting diamond education and helping people. It's helped me considerably and I hope it continues to help people.

 

[Mara]

welcome.




you may find the SEARCH tool located at the top of this page most helpful in researching this same discussion which has happened many times. type in HCA and other selective words and you will find many threads. the tool is very controversial for some, accepted by others. there is no one right answer. in fact there was a conversation about it last week. it tends to get very heated at times.




the search tool is pretty easy to use. good luck!

 

[valeria101]

----------------
On 7/8/2004 12:10:33 AM gimme wrote:



Does it really work??

----------------

It's supposed to make sense of a round brilliant's sarin report (or the excertpts given on GCAL, EGL or AGS reports). Otheriwse, what else is there to make any sense of those numbers

It works as soon as you understand what the limits of the tool are - and there is plenty of detail about them, about half of the glass. Some preffer the full part, some the empty. For me, the full part if just 51%

How about you?

 

[imback]

it is a fallacy. does no good, except by luck (in otherwords, by accident, it is possible that a diamond with a high hca score will perform well), and is likely to give false or misleading results. a completely arbitrary scoring system.

 

[oldminer]

imback:

I read your post and it sound like a Monty Python script.

The HCA works. It is limited by the accuracy of the Sarin or Ogi measurments and because not every detail of cutting can be taken into account. A diamond scoring low on the HCA will definitly be a poor light performer and one with a very high score will never be a poorly performing stone.

The difference between stones scoring in the top ranges may be completely invisible to anyone's eye, trained or not trained. In this regard I do agree with those who say this is not a perfect tool. Even Garry Holloway admits these limitations.

The HCA is a rapid separator of poor from medium from fine light performance stones. It is a filter, not a total selection device. Similar limitations are found in the Brilliancescope or the ISee2 devices which are very costly. The HCA is certainly priced better.

 

[pricescope]

Welcome back, David...

 

[fire&ice]

----------------
On 7/9/2004 11:00:27 AM imback wrote:

it is a fallacy. does no good, except by luck (in otherwords, by accident, it is possible that a diamond with a high hca score will perform well), and is likely to give false or misleading results. a completely arbitrary scoring system.----------------

Gosh, Imback, your last post was over THREE years ago. Your first post in 3 years & you come BACK to bash the HCA system. Why? And, what do you have to support such claim?

 

[Regular Guy]

David (or available others),

This follows my note to your site yesterday. You mention in your post here both sarin or OGI. Do these, as well as the Diamond Proportion Analyzer, all with reasonable reliability measure crown and pavillion angles?

 

[oldminer]

Ogi and Sarin give reasonable results. A diamond Proportion analyzer which fits in the ocular of a microscope or is a stand alone unit GIA sold does a rather poor job. I think there is a 2 degree error on those...Good tools in their day, but becoming passe'

 

[Superidealist]

On 7/9/2004 11:00:27 AM imback wrote:
it is a fallacy. does no good, except by luck (in otherwords, by accident, it is possible that a diamond with a high hca score will perform well), and is likely to give false or misleading results. a completely arbitrary scoring system.

To me, this doesn't sound very different from the BrillianceScope, which your site seems to support unquestioningly.

 

[Mara]

this voice of dissent is tinny at best, especially when couched in easily-penetrable anonymity...




welcome back, David T. have the grace to use your real name and show your real motives, eh?