DiamCalc favor please: to show off for my fiancee to be???

[hunter3316]

I''ve just purchased this stone based on all of the awsome accumlated knoledge and advise from this site. Could someone please put my diamond on the DiamCalc? And let me know the light leakage out-put and possibley a few predicted ideal scop images.. mabey even an ouput file for the "gem advisor"? That would be really awsome. I would like to show all this info to my girlfriend after she says yes! (Lets hope)

It scores ex-ex-ex-ex and 0.7 on the HCA.

Numbers:

Dem.:5.84X5.85X3.50
Depth:60
Table:57.2
Crown:33.3
Pavilian:40.6
Culet: None

Thanks guys, this site has been invaluble to me!
Dave

 

[Rhino]

Here are 2 possibilities out of hundreds. It is also likely that your minor facet variances may not be as precise as the attached file indicates. Only a professional optical analysis would reveal the truth. This first gem file is using your measurements with 50% stars and 78% lower girdles.

Rhino

 

[Rhino]

Here's the same specs with 60% stars and 81% lower girdles. Both appear to be very good among these 2 variations I've presented. You should consider getting an actual analysis done on this stone.

Peace,
Rhino

 

[DancinGirl]

Am I blind or is there nothing there? Come on Jonathan, don't let us down -- you're leaving me hanging!!

 

[Rhino]

LOL!!! Hey DAncin girl!!!

Check out the file attachements at the bottom of my message in the footers.

You gotta have GemAdvisor to open them though. The default file I attached are simulated FireScope images.

Good to cya here.

Rhino

 

[hunter3316]

with 50% stars and 78% lower girdles

Hey Rhino,

What does the above mean: Ive never heard of those??? "50%stars... "

Dave

 

[Rhino]

Here's a cool lighting condition I've been including in many of the stones we've been scanning in lately. It's under simulate jewelry store lighting. It's using the same measurements as the 2nd example I gave except the default light is not a sim FireScope but jewelry store lighting.

Open this file and hit the green play button.

This and disco lighting are my favorites.

Haha... is disco still around in Russia? That's where the software was made. I can just see Sergey and Yuri standing in a Russian disco tek with the pimp daddy hats on looking at diamonds! hehe

Rhino

 

[Rhino]

----------------
On 5/7/2003 11:50:28 PM hunter3316 wrote:

with 50% stars and 78% lower girdles

Hey Rhino,

What does the above mean: Ive never heard of those??? "50%stars... "

Dave----------------

Hi Hunter,

Yep. Ok ... in a nutshell. Before we begin keep in mind that there are 57-58 facets on a round brilliant cut diamond.

When you list crown angles of 33.3 degrees (or a Sarin or AGS Report for that matter), 33.3 degrees is only an average of 8 crown angles that are measured on the diamond. The 8 angles that are measured are specifically on the 8 bezel facets as depicted in this graphic. Your 33.3 degree average could consist of variations as small as a minimum crown angle of 33.1 and a maximum of 33.5. That would be evidence of excellent precision. However your diamond may have wild variances ranging from 32 degrees to 35 degrees averaging your 33.3. We would not know unless we personally examined the diamond. The diamond in this example has average crown angles of 34.3 degrees but the report is also telling us that the minimum is 34.1 and max is 34.5. That's tight. ... more to come ... (so far here are 8 facets accounted for)...

 

[Rhino]

Ok... now you got 8 pavilion mains as depicted in this graphic. The pavilion angles are measured off of these pavilion main facets. When you have the proper combomination (and internal precision) of pavilion mains with crown bezels this can form the "arrows" effect within the Hearts & Arrow diamonds. Pavilion mains make up the arrows. Again ... a Sarin or AGS Report only gives the "average" of those 8 pavilion angles. How wild they vary we wouldn't know unless it were personally inspected by a pro with the proper hardware.

Ok ... so with 8 crown bezels and 8 pavilion mains we've covered so far 16 out of 57 facets.

 

[Rhino]

The other facet covered in the info you provide is the table size. That is an average taken not on 8 measurements but only 4 as depicted in this graphic.

Your diamond has no culet facet so we don't have to worry about that so out of 57 facets on your diamond we only have details on 17 of those facets.

8 bezel.
8 pavilion mains
1 table.

What about the other 40 facets? The altering of those facets can dramatically affect the look (and even the brilliance/scintillation) of a diamond. That's why when someone asks for DiamCalc help I'm a little hesitant to respond because there are literally thousands of variations that can be shown and people like myself and Rich Sherwood DO NOT WANT TO MISLEAD. Most diamonds cut do not have the precision we are displaying in these graphics. So when you consider that we do not know the variances, nor do we know the details on those 40 other facets that make up the diamond it can (in alot of people's opinion including my own) dramatically affect the look and appearance of the diamond.

...

 

[Rhino]

Here are the star facets on the diamond depicted in yellow. 8 of them total. The lengthening or shortening of them affects the optics of the diamond.

 

[Rhino]

Your upper girdles. 16 of them. Combining the proper angles of the upper girdles with the proper lower girdles angles can reduce or eliminate leakage around the perimeter although this is very hard to detect with the human eye as the light return is usually weak in those areas of refelction. While the pavilion main/bezel angle is the most critical angle relationship within the diamond this is a relationship that only few cutters have recognized and done something about and my hat is off to them I know of only 3 factories in the world doing it (actually 4 when you consider 8* Japan).

One more and class is over for the night.

 

[Rhino]

And last but not least your pavilion halves or lower girdles. 16 of them too. With the crown bezels and pavilion mains I consider these facets to be equally as important. The measurements % and angles of the pavilion halves are crucial in the light return of a diamond as they too act as mirrors on the pavilion either directing light to the eye or away from it.

So in summary ...

8 crown bezel facets (upon which the crown angles and crown height are measured)
8 pavilion mains (upon which the pavilion angles and pavilion depth is measured)
1 table facet (the biggest facet on the diamond)
8 star facets on the crown
16 upper girdle facets
16 lower girdle facets
1 culet (if it's there) A culet will determine whether there are 57 or 58 facets.
----------------------------------
58 facets.

CLASS DISMISSED!

 

[hunter3316]

WOW, thats awsome Rhino!
Thanks so much for that info! I understand everything you wrote and the pics are great! However, while I know understand what you mean by stars and lower pavilians (minor facets), I still dont understand what 50% star facets implies. 50% of what? Mabey 50% of the crown angle???

Thanks again!
Hope Im not keeping you up to late!

 

[Rhino]

Just to demonstrate the effect on how the lower girdle measurements can affect the look of a stone here is an example using the average measurements you've provided (assuming perfect or near perfect optical symmetry), keeping your star facets at 55% ... the graphic on the left has lower girdles at 85% the graphic on the right changing them to 75%.

This DEFINETELY affects the appearance of the stone.

It is noble that there are websites and people offering DiamCalc services in an effort to help people but people should really be enlightened about these things too when they are seeking this kind of advice. If the wrong star/lower girdles measurements are being plugged into the software without the knowledge of those measurements they can be unintentionally misleading people with faulty information. If you note Rich does put a disclaimer on all his posts when he posts those images and wisely so.

My .02c.

Peace,
Rhino

 

[Rhino]

----------------
On 5/8/2003 12:46:16 AM hunter3316 wrote:
WOW, thats awsome Rhino!
Thanks so much for that info! I understand everything you wrote and the pics are great! However, while I know understand what you mean by stars and lower pavilians (minor facets), I still dont understand what 50% star facets implies. 50% of what? Mabey 50% of the crown angle???

Thanks again!
Hope Im not keeping you up to late!----------------

Good question hunter. Glad you're grasping this. Your reference point is the edge of the table (where the star facet begins) to the edge of the girdle. 50% would be the halfway point right where the point of the star facet meets the upper girdles. So a 50% star facet measurement would mean that the star facet reaches exactly half way from the edge of the table to the edge of the girdle. If the stars were 60% in lengh, that means they'd extend out further towards the girdle. If you'd like to see some microscope pictures of diamonds with short stars vs long stars and their optical results drop me an email. It's pretty neat stuff.

If I start posting links to diamonds in an effort to educate and teach some people get annoyed here and I want to keep Leonid on my good side.

Peace,
Rhino

 

[DancinGirl]

RHINO - check your email...grrr... don't make me come down to NY and spank you!

 

[69gm]

hi rhino,

where do you get GemAdvisor from? i know you sent me some stuff on my inquiry that i'd like to look at too!

thanks!

 

[hunter3316]

Thanks for the education Rhino!
I love these simulations! Theres just somthing about a computer analysis that just makes stuff more fun!

Thanks for your hard working input!

Peace.

 

[Richard Sherwood]

-----------
If the wrong star/lower girdles measurements are being plugged into
the software without the knowledge of those measurements they can be
unintentionally misleading people with faulty information.
-----------

Rhino, I understand where you're coming from on this, but wouldn't you agree that usually DiamCalc puts a diamond profile in the right ballpark as far as general light performance is concerned?

For example, showing the "ring of death" from a "steep-deep" stone, along with a weak performance from the girdle facets. Or a dark center from a deep pavilion stone, girdle reflection in a shallow stone, etc, etc, etc.

I know in two scenarios like you show above you're going to get different results, but in actuality you don't really see those two extremes that much, do you?

Would you agree that if you kept the minor facets within common profiles that the images and numbers are usually going to be a good indicator of the light performance of the stone?

Internet shoppers don't have the ability to "see" all the stones they're considering. The DiamCalc is another tool to help the consumer "see" a stone they're considering. Do you feel we shouldn't use it because of the minority of cases when it will be "off the mark"?

Okay, that's all my questions for ya right now.

 

[Rhino]

----------------
On 5/8/2003 1:32:26 AM DancinGirl wrote:

RHINO - check your email...grrr... don't make me come down to NY and spank you!

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

Hit me with your rhythm stick... HIT ME HIT ME.

Hehe... remember that ol song?

 

[Rhino]

----------------
On 5/8/2003 4:27:18 AM 69gm wrote:
hi rhino,

where do you get GemAdvisor from? i know you sent me some stuff on my inquiry that i'd like to look at too!

thanks!----------------

Right here hoss. https://www.pricescope.com/MSU/gadviser.asp

 

[Rhino]

No prob man and YES it does indeed make this hella more fun!!! I love it that we can post .gem files on pricescope.

Here's another fun thing which we are now incorporating into our services and that is "virtual comparisons". Here are 2 virtual models using the 2 examples I gave above hunter. Your dimensions, both with 55% stars, one with 75% lower girdles the other with 85% lower girdles. Open up this first one with Gem Advisor, put it into disco light and press play. Then open the next file, load it into disco light and press play having both GemAdvisors running at the same time ... get about an arm/arm and half lengths distance in front of your computer monitor and look at the visual difference between the 2 stones. Keep in mind that yours may be more similar to one than the other OR NEITHER but it's just cool stuff.

Rhino

----------------
On 5/8/2003 1:24

9 PM hunter3316 wrote:
Thanks for the education Rhino!
I love these simulations! Theres just somthing about a computer analysis that just makes stuff more fun!

Thanks for your hard working input!

Peace.----------------

 

[Rhino]

Here's the other. As you're looking at the 2 side by side look at how different the measurements of the lower girdles affect the look of the diamond. Even both stones get different GemAdvisor scores with the diamond having the longer lower girdles getting the better score out of the 2. Now you have a hint at one of the factors this cut geek looks for when purchasing his stones for inventory.

Peace,
Rhino

 

[Rhino]

----------------
On 5/8/2003 6

5:31 PM Richard Sherwood wrote:

-----------
If the wrong star/lower girdles measurements are being plugged into
the software without the knowledge of those measurements they can be
unintentionally misleading people with faulty information.
-----------

Rhino, I understand where you're coming from on this, but wouldn't you agree that usually DiamCalc puts a diamond profile in the right ballpark as far as general light performance is concerned?

Yea but the minor facets and the variances of those + the majors can completely change the appearance. I've done HCA's and DiamCalcs on diamonds before I've called them in for analysis with high hopes only to sometimes get a diamond that's shakaka.

For example, showing the "ring of death" from a "steep-deep" stone, along with a weak performance from the girdle facets. Or a dark center from a deep pavilion stone, girdle reflection in a shallow stone, etc, etc, etc.

I also hear where you're coming from too bro. Case in point our friend hunter. Both extremes I give would BOTH be good looking stones however they can vary in appearance. When I've showed clients these differences I have many who would choose one way or the other when given the choice.

I know in two scenarios like you show above you're going to get different results, but in actuality you don't really see those two extremes that much, do you?

Oh yes! And many of our clients have too who have been able to make the comparison. Admittedly some do not but the majority do indeed see it. Check out the virtual comparison I just loaded here for hunter. This is a difference that the average John Doe would be able to observe.

Would you agree that if you kept the minor facets within common profiles that the images and numbers are usually going to be a good indicator of the light performance of the stone?

Insofar as general light performance yes. However out here in cyber geek land we're dealing with people who WANT DETAILS and if they realize that minor facet measurements can seriously affect the appearance of a diamond they want to see it. Within the DiamCalc software it loads as a default 46% stars and 82% lower girdles. From my experience very few diamonds are cut with 46% stars coupled with 82% lower girdles. So when you or anyone with DiamCalc help people here (and Rich, that is to be commended) I notice you're loading the proportions they are giving you with 46% stars and 82% lower girdles which is probably not what they have. Also for sites using the DiamCalc software in their sales and are not plugging in the proper star and lower girdle measurements ... this is not really showing the stone they are trying to sell in an accurate light. I'm not saying this to hurt anyone's biz but just to improve upon the accuracy upon what they are presenting. People who are using the software to "help" can only be commended but I would add, to do so with the proper measurements.

Internet shoppers don't have the ability to "see" all the stones they're considering. The DiamCalc is another tool to help the consumer "see" a stone they're considering. Do you feel we shouldn't use it because of the minority of cases when it will be "off the mark"?

It really depends Rich. It depends upon the variances which can be very wild or very tight. It depends upon whether that stone has extreme measurements in the lower girdles, stars or upper girdles. So companies charge an exhuberant amount more for tweaking their minors. YES INDEED DiamCalc is great. It's really quite amazing and does indeed help people see virtually what they are getting but my whole point to hunter is that what we are presenting can be dramatically different than what he actually has. To some people perhaps these differences don't mean much but "to me" it does. The virtual comparison shows it best. My advice to anyone seeking to give advice with DiamCalc is to show the client 2 extremes or more as you see fit. One with a short star/lower girdle combo, one with a long star lower girdle combo and perhaps both combos with tight variances and one with wild variances and let them know they can have a stone closer to one than the other or none of the above. Haha! Rich there are times when minor facet measurements can really affect the light output one way or the other. Name of the game my friend is when we don't have all the details is to play it safe. This is why I would NEVER NEVER NEVER personally purchase or recommend a diamond that I do not inspect myself.

Okay, that's all my questions for ya right now.

Peace,
Rhino

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

 

[hunter3316]

So Rhino,
when you say the minor facets change the "appearence" of a stone, how are you defining appearence?

Are you talking about sintilation, light return, reflection patterns... etc...?

Or mabey a combination of all of the above!

Thanks again!

 

[Richard Sherwood]

-----------
I notice you're loading the proportions they are giving you with 46%
stars and 82% lower girdles which is probably not what they have.
-----------

Actually, I vary the star and lower girdle percentages for almost every profile I post. I look at the general proportions of the cut, and then try to use a range of star and lower girdle percentages that I think will fall in the middle-of-the-road for those proportions.

For example, the range of lower girdle percentages you use in the examples above are ranges which you USUALLY will not run across in the vast majority of stones, especially fine makes. If you run across a stone with ideal proportions or premium proportions for example, the chance that a cutter used such ungainly lower girdle facet extremes is very small.

If you do hit a middle of the road profile of lower girdle and star facet lengths, then usually you're going to be pretty close to the overall performance of the stone, even if it strays away from the profile a bit. I know that differences will come up, but usually they don't affect the overall performance of the stone to a degree that makes a drastic difference in the light return performance.

I know that to a person like yourself who pursues perfection that "pretty close" is not good enough, but in reality "pretty close" is pretty good in helping people make an intelligent decision when going through the weeding out process. When they arrive at a good candidate, then it's time to hone in on the exacts.