GIA XXX with HCA ex-ex-ex-vg

[ikonos]

What are the chances a GIA XXX stone with a HCA score under 2 and HCA result of ex-ex-ex-vg will not be an excellent choice? The GIA certificate indicates it is an excellent cut with excellent polish and symmetry. At this point I dont have access to Ideal Scope, ASET or Sarin reports. Assuming I may or may not be able to get them from the vendor, what other aspects should be considered when buying online?

Thanks
Ik.

 

[jaz464]

Can you list the diamond''s specs for us please?

 

[Skippy123]

Date: 7/13/2008 4:58:20 PM
Author:ikonos
What are the chances a GIA XXX stone with a HCA score under 2 and HCA result of ex-ex-ex-vg will not be an excellent choice? The GIA certificate indicates it is an excellent cut with excellent polish and symmetry. At this point I dont have access to Ideal Scope, ASET or Sarin reports. Assuming I may or may not be able to get them from the vendor, what other aspects should be considered when buying online?

Thanks
Ik.

I saw the numbers in your other thread. What type of return policy do they have? I guess if they can''t get you a picture or IS image I would want to make sure I could return the stone if you are not happy with it.

 

[ikonos]

I want this to be an informational thread with out focusing on a particular stone to get the best out of the discussion. At this point I have few stones in mind and once I narrow them down, I will post the numbers.

 

[ikonos]

Skippy - Numbers from my other thread? Which thread are you talking about?

 

[Skippy123]

Date: 7/13/2008 5:30:12 PM
Author: ikonos
Skippy - Numbers from my other thread? Which thread are you talking about?

Ops, sorry, I got you confused with someone who had ex-ex-ex-vg, on the HCA.

The HCA is a great tool for weeding out stones.

 

[honey22]

Date: 7/13/2008 5:14:01 PM
Author: ikonos
I want this to be an informational thread with out focusing on a particular stone to get the best out of the discussion. At this point I have few stones in mind and once I narrow them down, I will post the numbers.

I guess we really can''t answer this question properly without the numbers. Some GIA XXX I would pass on despite a good HCA score, whereas some I would go for. I think if the numbers were really tight, then I would say you are probably safe, but there are certainly some combos that I wouldn''t go for, and they would still score well on the HCA. So, you really can''t say yes to all stones that fall under 2 on the HCA, as they are some I wouldn''t want at all.

If you really want accurate advice, you need to post as much info as possible, so people can make ''informed'' answers to your questions.

Hope this helps.

 

[ikonos]

honey22 - Sorry for not providing the numbers yet as I am still short listing them. And that is where I am trying to gather more info on what to look for to narrow down the list.

Can you give me more info on when you will not go for a GIA XXX stone with excellent HCA scores?

 

[ikonos]

Here are some numbers for stones with VS2 or better clarity. All GIA graded stones.

Stone1:
Depth: 62.1%, Table: 55%, Crown Angle: 35.5, Pavilion Angle: 40.6
Star Length: 50%, Lower Half: 75%
Cut: Excellent
Polish: Ex Symmetry: Ex
Gridle: Thin-Medium, Faceted
Comments: Cloud
HCA: 1.3-ex-ex-ex-vg

Stone2:
Depth: 60.7%, Table: 57%, Crown Angle: 33, Pavilion Angle: 40.8
Star Lengh: 50%, Lower Half: 80%
Cut: Excellent
Polish: Ex, Symmetry: Ex
Gridle: Medium-Slightly Thick, Faceted
Comments: Cloud, Feather, Needle
HCA: 0.8-ex-ex-ex-vg


Stone3:
D: 60.7%, T: 56%, CA: 33, PA: 41,
Star Length: 45%, Lower Half: 80%
Cut: Excellent
Polish: Ex, Symmetry: Ex
Gridle: Med, Faceted
Comments: Cloud, Feather
HCA: 0.6-ex-ex-ex-vg


Other than color, clarity and price, what else should I be focussing on? Which of these three stones is a better option and why?

Thanks
Ik.

 

[John P]

Date: 7/13/2008 8:45:05 PM
Author: ikonos
Here are some numbers for stones with VS2 or better clarity. All GIA graded stones.

Stone1:
Depth: 62.1%, Table: 55%, Crown Angle: 35.5, Pavilion Angle: 40.6
Star Length: 50%, Lower Half: 75%
Cut: Excellent
Polish: Ex Symmetry: Ex
Gridle: Thin-Medium, Faceted
Comments: Cloud
HCA: 1.3-ex-ex-ex-vg

Stone2:
Depth: 60.7%, Table: 57%, Crown Angle: 33, Pavilion Angle: 40.8
Star Lengh: 50%, Lower Half: 80%
Cut: Excellent
Polish: Ex, Symmetry: Ex
Gridle: Medium-Slightly Thick, Faceted
Comments: Cloud, Feather, Needle
HCA: 0.8-ex-ex-ex-vg


Stone3:
D: 60.7%, T: 56%, CA: 33, PA: 41,
Star Length: 45%, Lower Half: 80%
Cut: Excellent
Polish: Ex, Symmetry: Ex
Gridle: Med, Faceted
Comments: Cloud, Feather
HCA: 0.6-ex-ex-ex-vg


Other than color, clarity and price, what else should I be focussing on? Which of these three stones is a better option and why?

Thanks
Ik.

Numbers by themselves are like a chalk outline. We need imagery to give more input. Based on this information the HCA does not dismiss any of these diamonds out of hand, and neither would I. My opinion of which is most promising could change depending on particulars best seen in an ideal-scope or ASET image.

Example; number 1 could be nicely balanced with a tendancy for fire over brightness, but I'd want to know if the lower halves were closer to 73 or 77% (75% is a rounded number) and the high crown might be a concern depending on cut consistency. These are particulars that are best answered by seeing actual imagery.

None of those you listed are in the "danger zone" that lies at the steep/deep end of the GIA EX range.

 

[ikonos]

John,

Thanks for your input. What are considered high and low angles for crown and pavilion? I am trying to weed out as many as possible based on numbers before asking for imagery. I am not sure if that is a good approach but hopefully it works.

Thanks
Ik.

 

[honey22]

Date: 7/13/2008 6:37:12 PM
Author: ikonos
honey22 - Sorry for not providing the numbers yet as I am still short listing them. And that is where I am trying to gather more info on what to look for to narrow down the list.

Can you give me more info on when you will not go for a GIA XXX stone with excellent HCA scores?

I am a bit obsessive you could say, so I really love the ''super ideals'' - RBs with really tight numbers that fall into the AGS Ideal category, which is a bit stricter than GIA excellent. I personally would steer away from stones that have are a bit deep, have a larger table size than I would prefer, ie. 58 and above etc. These are not necessarily poor stones, these are just my preferences. If I am going to spend money, I want to get the best possible cut I can, and that''s why I went for a branded cut.

Lorelei is always posting a set of numbers that you can use when looking for stones. These are likely to be great performing stones, and then we would suggest an IS image to back these numbers up. I will try and find one of her posts, she is terribly helpful!

 

[honey22]

Date: 7/14/2008 2:06:14 AM
Author: honey22

Date: 7/13/2008 6:37:12 PM
Author: ikonos
honey22 - Sorry for not providing the numbers yet as I am still short listing them. And that is where I am trying to gather more info on what to look for to narrow down the list.

Can you give me more info on when you will not go for a GIA XXX stone with excellent HCA scores?

I am a bit obsessive you could say, so I really love the ''super ideals'' - RBs with really tight numbers that fall into the AGS Ideal category, which is a bit stricter than GIA excellent. I personally would steer away from stones that have are a bit deep, have a larger table size than I would prefer, ie. 58 and above etc. These are not necessarily poor stones, these are just my preferences. If I am going to spend money, I want to get the best possible cut I can, and that''s why I went for a branded cut.

Lorelei is always posting a set of numbers that you can use when looking for stones. These are likely to be great performing stones, and then we would suggest an IS image to back these numbers up. I will try and find one of her posts, she is terribly helpful!

Can''t find those darn numbers, I should know them, but Lorelei has a much more succint way of putting them. Are you out there Lorelei?! Can you please post your famous numbers?!

 

[Lorelei]

Date: 7/14/2008 2:15:31 AM
Author: honey22

Date: 7/14/2008 2:06:14 AM
Author: honey22

Date: 7/13/2008 6:37:12 PM
Author: ikonos
honey22 - Sorry for not providing the numbers yet as I am still short listing them. And that is where I am trying to gather more info on what to look for to narrow down the list.

Can you give me more info on when you will not go for a GIA XXX stone with excellent HCA scores?

I am a bit obsessive you could say, so I really love the 'super ideals' - RBs with really tight numbers that fall into the AGS Ideal category, which is a bit stricter than GIA excellent. I personally would steer away from stones that have are a bit deep, have a larger table size than I would prefer, ie. 58 and above etc. These are not necessarily poor stones, these are just my preferences. If I am going to spend money, I want to get the best possible cut I can, and that's why I went for a branded cut.

Lorelei is always posting a set of numbers that you can use when looking for stones. These are likely to be great performing stones, and then we would suggest an IS image to back these numbers up. I will try and find one of her posts, she is terribly helpful!

Can't find those darn numbers, I should know them, but Lorelei has a much more succint way of putting them. Are you out there Lorelei?! Can you please post your famous numbers?!

Here I is!

Ok - here you go!

depth - 60 - 62% ( my cutoff is 62.4% thereabouts)
table - 54- 57%
crown angle- 34 - 35 degrees
pavilion angle - 40.6 - 41

* with crown and pavilion angles in critical areas towards the shallower ( CA 34- PA 40.6) and steeper ends, as JP cautions ( CA 35 - PA 41) evaluate carefully with Idealscope and trusted vendor input to make sure the angles are complementary in that particular diamond.
polish and symmetry - very good and up
girdle - avoid extremes such as thin to very thick for example, look for thin to slightly thick, medium etc.

* NB - these numbers are a good range to use, but also proportions which are outside of these in some circumstances can still produce a beautiful diamond, so make use of HCA, Idealscope, trusted vendor opinion and lastly your own eyes.

 

[honey22]

Thanks Lorelei! I have to figure out a way to save those for handy future reference!

 

[Lorelei]

Date: 7/14/2008 5:03:47 AM
Author: honey22

Thanks Lorelei! I have to figure out a way to save those for handy future reference!

Most welcome!

 

[ikonos]

Thanks for the info. Are there similar numbers for star length and lower half?

 

[arjunajane]

Date: 7/14/2008 9:00:46 PM
Author: ikonos
Thanks for the info. Are there similar numbers for star length and lower half?

I believe there are acceptable ranges when combined with the other angles, but then you are really getting into the "personal preference" area..ie. different flavours of H&A for different people.
Best to decide first what your eyes like by looking at stones in pics/videos online, or better in real life. Then search for ones with those or similiar specs online.
Please no offence, but once you buy a diamond all these numbers etc mean nothing. You need to start looking with your eyes, and personally if my vendor isn''t able to readily supply IS images at the minimum, it would just make it too much work.