Narrow down to this rock - Need your advice

[Tim]

I have narrowed down my search to this stone. Would you please comment on this stone. It displays crisp and sharp hearts and arrows.

GIA certificate
Weight: 1.22 ct
Color: F
Clarity: VVS2
Symmetry: Exellence
Polish: Exellence
Fluorescence: Faint

Diameter 6.86 mm - 6.88 mm
Diam Dev: 0.3%
Table Size: 56.6%
Total Depth: 61.7%
Crown Angle: 35.0 degree
Crown Height: 15.3%
Pav Angle: 41.1 degree
Pav Depth: 43.4%
Cullet Size: 0.6% - Very Small
Girdle Min: 0.6% Thin
Girdle Max: 1.46% Medium
Star/UppeRatio: 55:45

Crown 35.2,35.3,35.1,35.5,35.2,35.3,35.1,35.2 degree
Pavillion 41.2,41.2,41.1,41.0,41.0,41.0,41.0,41.1 degree

Thank you for your help.

Tim

 

[Rhino]

I don't doubt it has a good H&A pattern and that will to an extent guarantee good fire within the stone but I know from personal experience that when you take crown angles around 35 degrees and couple them with pavilion angles greater than 41 degrees this is a recipe for an H&A with a serious ring of death under the table (ie. too much light leakage for my taste).

Just running a cursory review on the HCA it gets a 2.9 which is not that good for a stone that is an H&A and confirms my suspicions. The price you're getting though reflects this and at the last jewelery show I was at witnessed MANY stones with these combinations of angles that were H&A's.

My .02c
Rhino

 

[sylvesterii]

forgive me if i seem a bit confused, but was that a typo in the numbers when you said that the diameter varried from 6.86-8.88, should that have read 6.86-6.88? otherwise i may have an inkling this is an oval stone? just curious, because i have never seen such detailed notes regarding anything but a round...

 

[Tim]

Rhino,

Thank you for your comment. Can you please elaborate on that a little bit more please. Does anyone else agree with Rhino? Please help!

Tim

 

[Richard Sherwood]

This is probably a good looking stone Tim, but the crown and pavilion angle relationship creates a moderate amount of light leakage just inside the table which Rhino has dubbed the "ring of death".

Following are some simulated images which illustrate this. The first is an IdealScope image showing the light leakage as a white area just inside the table. The second is a photoreal image which shows how this leakage translates into a moderately darker area just inside the table. In my experience, this area looks darker on the photoreal image than it does in real life, but it's still there.

The third image is a simulated IdealScope image of a similar diamond which has had the crown angle reduced to 34 degrees and the pavilion angle reduced to 40.5 degrees. This is a excellent combination of crown and pavilion angles which produces an HCA score of 0.4. Not all stones will produce such low scores, with plenty still looking great to the eye, but generally if you can stay a little under 35 degrees on the crown angle and a little under 41 degrees on the pavilion angle you will produce a more brilliant and fiery stone.

The HCA cut advisor is a good tool for sifting through the possibilities and eliminating the poor perfomers. NiceIce also has what they call a "sweet spot" profile of top-performing proportions which is helpful. Perhaps they'll post it on here when they run across this topic.

When you get down to the nitty gritty, you can view the light return performance with your own eyes by using one of Garry Holloway's IdealScopes, which can be purchased for $30 (including calibration cz) through the menu at the top of your screen.

I wouldn't call the stone you're looking at a poor performer (2.9 HCA isn't half bad), but it just isn't good enough to get a cut geek like Rhino grinning. But then again, Rhino's the kind of guy that would toss Demi Moore out of bed if she was having a bad hair day.

 

[Richard Sherwood]

35'/41.1' simulated idealscope

 

[Richard Sherwood]

35'/41.1' simulated photoreal

 

[Richard Sherwood]

34'/40.5' simulated idealscope

 

[Richard Sherwood]

34'/40.5' simulated photoreal

 

[DBOF]

You would think after hearing all that you were about to buy a ticket on the Titanic

Really, take a look and see, don`t be scared to look and decide for yourself.

Number roulette can be like a blind man in a house of mirrors.
You can get three different sets of numbers on the same diamond from different sarins,and even the same sarin sometimes, so which one do we bet on

I myself think diamonds should be seen before heard.


Good luck on your quest.

Brad

 

[aljdewey]

----------------
On 8/10/2003 7:44:54 PM DBOF wrote:
You would think after hearing all that you were about to buy a ticket on the Titanic

Really, take a look and see, don`t be scared to look and decide for yourself.

Number roulette can be like a blind man in a house of mirrors.
You can get three different sets of numbers on the same diamond from different sarins,and even the same sarin sometimes, so which one do we bet on

I myself think diamonds should be seen before heard.
----------------

Hi, DBOF: First, GREAT TO SEE YOU posting here. It's a pleasure to have you contributing!

I think most of us here would agree that numbers are not the "be all, end all"....in the end, it's most important what delights the eye.

However, I do think it's cogent to consider numbers in narrowing down one's choices to a manageable set of parameters. There are literally *thousands* of diamonds out there, and one has to narrow down the field in some way. For some, it's carat weight (I want a stone between 1.5 & 2 cts).....for others, it's cut (numbers).

Regarding your following comment, "You would think after hearing all that you were about to buy a ticket on the Titanic".........I'm surprised. Your comments suggests that the responses from Rhino & Richard were of an alarmist nature or suggesting that the stone was horrible. I don't infer that from their comments at all.

Tim asked for comments on the stone. Rhino replied that these angles typically result in serious light leakage, which isn't HIS tastes, and that the HCA score wasn't that good for an H&A stone. He also fairly noted, though, that it appeared to be priced accordingly. Richard concurred that the stone would like exhibit light leakage, but went on to say that the stone wasn't a poor performer per se.

I think both assessments were exceedingly fair.....it isn't the most stunning model of an H&A stone. However, neither of them told him it was a dog, and neither of them told him it would be a poor purchase.

 

[bling]

How close can you get to those magic numbers before you get light leakage..
for example, i am looking at a stone that has a pavillion angle for 40.9 (which is pretty close to the 41) and crown agle of 34.4. would this daimond still get good light return even though the pavillion angle is almost 41? it too is a H&A ideal cut. Any thoughts? Thanks!

Theres just so much to be learned here..

 

[Richard Sherwood]

What's the table size, Bling? And how big's the culet?

 

[Boulder]

----------------
But then again, Rhino's the kind of guy that would toss Demi Moore out of bed if she was having a bad hair day.
----------------

 

[DBOF]

thanks aljdewey You don`t think the *ring of death* comment doesn`t sound horrible ?

Truthfully I don`t think anyone could really say what a stone looks like without seeing it.
I agree that to an extent that numbers are helpful for narrowing down choices, but we must realize these machines aren`t perfect and vary from machine to machine, so external measuring can`t always predict what a diamond will look like.
It is quite possible for the same stone to get different sarin readings , and therefore with numerical data alone one can not conclude with out a doubt what the diamond will look like. The pavilion angle/crown angles can read a few decimals different on another machine, but the stone will remain the same.

I had a larger stone I got in for stock last week with similar numbers, that is just gorgeous, (no ring of death either)

but if someone was just going by this info alone they wouldnt even appreciate it.

Brad

 

[bling]

Table size is 55 and culet is 0.6. Thanks!

 

[Garry H (Cut Nut)]

Brad that sounds like you would like to sleep with Demi on any day

Want to post us some data and images on that bad hair stone you saw?

As for the Sarin variations - it is one reason why I request people use Sarin by preference over Ogi. Ogi do not get the accuracy on pavilion angles that I wuld like.

There is more variation in crown angle and table size data than there is in pavilion angle from Sarin devices.

A 0,1 degree varation in pavilion angle is more critical than either a 1.0% table or 0.5% crown angle variance.

I find it interesting too that you have not been here for a long time, and when you do appear you attack DiamCalc and HCA. HCA has always been offered as a preselection method to weed out better stones. If as you say people may miss a few border line stones that look good, what about all the so called off makes that are truly beautiful like small table >36 crown 40 degree pavilions and 32-33 crowns with 41 degree pavilions? Without HCA or Ideal-Scopes many people would never have given these beautiful stones a second look.

 

[DBOF]

I feel like Jackie Chan walking into the pool room scene. " I don`t want trouble"

I`m not attacking DiamCalc and HCA. I don`t think consumers need to be scared away by *ring of death* comments though.

You know sarin`s limitations I`m sure.

Sure I`m game, if you keep it friendly.

Brad

 

[aljdewey]

----------------
On 8/11/2003 DBOFwrote:
You don`t think the *ring of death* comment doesn`t sound horrible ?

Truthfully I don`t think anyone could really say what a stone looks like without seeing it.
I agree that to an extent that numbers are helpful for narrowing down choices, but we must realize these machines aren`t perfect and vary from machine to machine, so external measuring can`t always predict what a diamond will look like.
It is quite possible for the same stone to get different sarin readings , and therefore with numerical data alone one can not conclude with out a doubt what the diamond will look like. The pavilion angle/crown angles can read a few decimals different on another machine, but the stone will remain the same.

I had a larger stone I got in for stock last week with similar numbers, that is just gorgeous, (no ring of death either)

but if someone was just going by this info alone they wouldnt even appreciate it
-------------

DBOF: No, I don't think the "ring of death" comment is horrible because the regulars here all know it to be a tongue in cheek description of light leakage in a ring under the table. Where you're new to posting here, you may not have known it to be a tongue in cheek comment.

Again, none of these guys said "don't buy it" or "what a sh*tty stone"; they both commented that the numbers would suggest there would be leakage. NOT that there IS leakage, but that they would anticipate leakage because such stones typically (not always) exhibit leakage.

I realize what you're saying about the numbers.......they don't tell the full story. Agreed.....wholeheartedly. But you have to understand that people come here asking for opinions based on those #s. Shy of physically viewing the stones...which isn't possible in this venue....that's all one has to go on. Could a stone with those numbers still be a great performer? OF COURSE it could.....the same way that a stone with great numbers can still be optically challenged.

As a matter of practice, the vendors and regular participants here have usually discouraged customers from relying solely on numbers or from allowing numbers to supercede what the eye sees. No one said the measuring machines were perfect, and most of the consumers are astute enough to realize that.

At the end of the day, these guys were just offering their best opinions based on the limited information given, and they gave fair opinions......in my humble opinion.

 

[aljdewey]

-------------
On 8/11/2003 4:37:22 PM Cut Nut wrote:

I find it interesting too that you have not been here for a long time, and when you do appear you attack DiamCalc and HCA.

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

Garry, that's a ludicrous stretch of the imagination on your part. In no way did DBOF "attack" HCA......they didn't say one word about HCA or any other specific program. What they said was that numbers (ANY numbers) don't tell the full story, and they're 100% correct in that statement.

They said that different devices often produce variances in measurements significant enough that the "numbers" aren't the "be all, end all"......and they're right. We've all read posts asking "why aren't the Sarin dimensions identical to the dimensions listed on my cert?" The numbers are meant as guidelines, not as guarantees.

In short, you're assuming harm where there was none intended. I don't know the back history with you guys, but from a consumer's viewpoint, I value the addition of more professional opinions here (even when they differ). It's how the rest of us learn.

I really hope that personal agendas (if there are any) don't discourage contributions from folks like DBOF, GOG, etc. In that situation, we would all lose.

 

[Tim]

Gentlement,

We have gone off topic long enough already. Everyone has a good point. I am planning to visit the store again and look at the stone again. How do recognize this light leakage with my bare eyes? Should I be seeing a dark table?

Apart from the fact that it's not as brilliant as it should be, this stone has great proportions. With the EX/EX finish and symmetry, it looks flawless. Is there something official (a website, research paper) about this 35/41 light leakage. I want to show it to the vendor to negotiate the price if I ever decide to buy this stone.

Thank you all for your help.

Tim

 

[Richard Sherwood]

-----------
How do recognize this light leakage with my bare eyes? Should I be
seeing a dark table?
-----------

The area to observe (as illustrated in the images above) is just inside the table. It's more easily seen in diffused lighting or fluorescent lighting than under strong incandescent lighting. A lighting environment like you find in an airport bathroom is perfect.

It's a subtle thing, which for the layperson is easier seen when comparing it next to a stone which doesn't have the effect. Once you've spotted it though and gotten used to it, you can spot it everytime in different stones you look at. It's very common, I see it almost everyday. Ten years from now you'll see it less and less, because optical performance is becoming more well known with the advent of increased cut awareness which is beginning to disseminate throughout the diamond community.

With an IdealScope you can spot the effect right away, because of the contrasting colors created.

The ideal-scope tutorial at the top of the menu above gives you a lot of examples of the different light leakage problems common in most diamonds, but doesn't specifically address the 35'/41+' syndrome which has become known on this forum as the "steep & deep" syndrome, accompanied by Rhino's dramatic "ring of death" description. If you were to mention these terms to the vast majority of diamond dealers, they would look at you and say "Huh?".

That said, you could probably pull up a fair amount of info regarding this particular crown/pavilion relationship by doing a PriceScope search for "steep & deep".

Again, we're talking about nuances here, which should figure into your judgement like any other of the "four c's". It's like deciding if you'd prefer a better cut G color over a lesser cut F. The color, clarity, and technical symmetry of the stone you're considering is awesome, and the optical performance is probably "pretty good". All in all, not a bad stone.

 

[Richard Sherwood]

Hi Brad. It's nice to see you posting on PriceScope. If you do a search, you'll find many consumer testimonials speaking highly of you, your mate, and DBOF. I hope you stick around.

-----------
I had a larger stone I got in for stock last week with similar
numbers, that is just gorgeous, (no ring of death either)
-----------

If you're saying the similar numbers are 35' crown angles and 41+' pavilion angles (without at least moderate leakage inside the table), I'd love to see an IdealScope or FireScope image photo of the stone.

In my experience that combo almost always lends itself to light leakage inside the table.

 

[Richard Sherwood]

Bling, the 55 table, 34.4' crown, 40.9' pavilion, 0.6% culet combination you listed works good.

A 1.3 on the HCA, it escapes the light leakage inside the table we've been talking about. Maybe we should rename it the "ring of wimpiness".

A simulated IdealScope image follows.

-----------
IdealScope- In general, the darker pink areas indicate areas of greater light return, with the lighter pink areas indicating areas of lesser light return. The black areas indicate areas of greater contrast, with the gray areas indicating areas of lesser contrast. The white areas indicate areas of light leakage. A good explanation of the IdealScope image along with examples can be found at https://www.pricescope.com/idealscope_indx.asp

Disclaimer- The facet arrangement and symmetry of the image will probably vary from your actual diamond, which may affect the light performance indicated, sometimes dramatically. The image shown has perfect symmetry, which is rare, and the star facet/lower girdle facet lengths may vary from your diamond. The computer simulation is reproduced best when the actual diamond is being viewed and the image "tweaked" to the appearance of the diamond, or when the Sarin data is downloaded directly into the program. However, this "blind" reproduction should be helpful in indicating the major light performance aspects.
-----------

 

[Richard Sherwood]

Bling's IdealScope simulated image

 

[Rhino]

Haha... HEY BRAD!!! Believe me I had no idea this was a stone of yours (still not 100% sure but judging from your response I'm assuming it is). Just giving my .02c with the limited info (although very good info from our poster Tim). It's good to see ya here and hope to see more of ya. I meant no harm with the "ring of death" comment but as aljdewey pointed out it's a term we've come to know here regarding stones that have that ring of white leakage under the table which is produced from stones similar to the proportions like Tim listed. Al expressed my sentiments exactly.

Aljdewey ... you have an uncanny way of hitting the nail precisely on the head. Your words express my thoughts exactly. (me hears tune of Twilight Zone in the background).

Hey Rich!!! Sorry I'm not posting as often as I'd like to here. We came back off vacation last week to a ton of work and had many many visitors from both posters and lurkers that we helped so my time is totally consumed lately with email, helping people in the store and scanning, analyzing and taking pics. Your answers to Tim are my thoughts exactly and when I found myself trying to open my DiamCalc software on my laptop I had left my HASP KEY on the computer at work so my hands were tied. Thanks for explaining what I meant about the ring of death.

Bling ... Rich answered you right on. Your 34.4 degree crown angles coupled with a 40.9 pavilion angle IS an excellent combo. Other questions to be raised at that point (at least in my own mind) is

a. How tight are the variances?
b. Including the minor facets
c. What are the measurements of the minor facets?
d. How is it's optical symmetry (ie. is it an H&A)?
e. If it is ... photo evidence and nothing less.

Those are questions that go off in my geeky mind.

From the numbers it sounds like you're off to a good start though.

Peace,
Rhino

 

[Garry H (Cut Nut)]

I'm sorry, Aljdewey... Brad has never liked HCA much.