Hearts and Arrow question

[swl]

Hi everyone! I have noticed most diamonds that demonstrates H&A scores 1.3 or below in the holloway cut adiver. So my question is : is it safe to say for venter that do not offer H&A diamonds, a diamond that scores .8 in the Holloway cut adviser will most likely demonstrates an excellent H&A pattern? Better fire and light return compare to diamonds that scores 1.8?

I know the cut adviser is a tool to select better diamonds, I just want to learn more about it

 

[kcoursolle]

Date: 4/4/2009 1:36:22 AM
Author:swl
Hi everyone! I have noticed most diamonds that demonstrates H&A scores 1.3 or below in the holloway cut adiver. So my question is : is it safe to say for venter that do not offer H&A diamonds, a diamond that scores .8 in the Holloway cut adviser will most likely demonstrates an excellent H&A pattern? Better fire and light return compare to diamonds that scores 1.8?

I know the cut adviser is a tool to select better diamonds, I just want to learn more about it

Nope, it''s not appropriate to say that. There isn''t any reason to believe that a .8 is better than a 1.8. Basically the HCA should be used as a weed out tool to weed out anything over 2.0. Then from there you need to look at other criteria to *choose* your stone.

 

[swl]

Date: 4/4/2009 2:53:27 AM
Author: kcoursolle

Date: 4/4/2009 1:36:22 AM

Author:swl

Hi everyone! I have noticed most diamonds that demonstrates H&A scores 1.3 or below in the holloway cut adiver. So my question is : is it safe to say for venter that do not offer H&A diamonds, a diamond that scores .8 in the Holloway cut adviser will most likely demonstrates an excellent H&A pattern? Better fire and light return compare to diamonds that scores 1.8?


I know the cut adviser is a tool to select better diamonds, I just want to learn more about it

Nope, it''s not appropriate to say that. There isn''t any reason to believe that a .8 is better than a 1.8. Basically the HCA should be used as a weed out tool to weed out anything over 2.0. Then from there you need to look at other criteria to *choose* your stone.

i see. Is it correct to say there is no difference what so ever between a stone that scored .8 and a 1.8 in the cut adviser?

 

[stone-cold11]

H&A pattern is only a measure of optical symmetry, totally different from optical performance. A H&A diamond can be quite badly cut for optical performance, so score high on the HCA and a stone scoring low on the HCA might not have H&A pattern. There is no correlation between the two.

The score on the HCA is a rejection tool based on average numbers of the crown and pavilion angles of 8 facets each. And with the GIA, is a rounded number of 0.5 for the crown angles and 0.2 for the pavilion angles. So anything score below a 2 is worth considering. That said, depending on the location of the x on the HCA plot further information, such as obstruction issue can be predicted.

 

[Lorelei]

Date: 4/4/2009 3:53:17 AM
Author: Stone-cold11
H&A pattern is only a measure of optical symmetry, totally different from optical performance. A H&A diamond can be quite badly cut for optical performance, so score high on the HCA and a stone scoring low on the HCA might not have H&A pattern. There is no correlation between the two.

The score on the HCA is a rejection tool based on average numbers of the crown and pavilion angles of 8 facets each. And with the GIA, is a rounded number of 0.5 for the crown angles and 0.2 for the pavilion angles. So anything score below a 2 is worth considering. That said, depending on the location of the x on the HCA plot further information, such as obstruction issue can be predicted.

Exactly.

Also optical symmetry is not the same as lab graded symmetry where all the facets and physical symmetry of the diamond is considered. The proportions are the main engines which drive the light return and ultimately the beauty and sparkle you see. The HCA is used for first round elimination only - not for selection, as it is not possible to say with any certainty that any diamond WILL behave in a certain way without inspecting it, the aim is to score below 2 then evaluate from there using ASET or Idealscope images.

You say you want further reading on the HCA so I would suggest this page, bear in mind these are guidelines only and the HCA is not used for selection as said previously and does not replace skilled evaluation by a trusted vendor or appraiser.

http://diamonds.pricescope.com/ideal.asp