Why do some diamonds look dark inside?

[Daniel B]

I saw Someone''s ring today and she said it was ags000, but it (facets inside) looked black, or very dark. It did not look very appealing at all. What is the reason for this? Please let me know because i want to avoid this at all cost!

 

[strmrdr]

could be a few different things, what were the black areas shaped like?

 

[Daniel B]

They were sorta like triangular, maybe the arrows or facets? What could all of the possibilities be?

 

[strmrdr]

one of 2 things likely:

short lgf%
too shallow a pavilion.

or a combo of the 2.

 

[decodelighted]

Or ... it might really be the much heralded arrows we hear so much about. They just don''t appeal to everyone (myself included). That level of contrast, even in an AGS 000, isn''t pleasing to my eye.

 

[strmrdr]

short lgf%

 

[strmrdr]

80% lgf, one of my favorite spots.

 

[strmrdr]

shallow pavilion 80% lgf

 

[strmrdr]

puke combo, shallow pavilion and short lgf

 

[Daniel B]

"Puke combo", i like that

So, you like the smaller twinkles of light storm? What would be the best combo for not seeing the dark areas-- it makes me wanna puke--

and what constitutes as a shallow pav? Thanks

. . . you may be right decode!

 

[strmrdr]

under 40.6 is shallow and 40.6 is borderline.
sometimes good, sometimes bad.

 

[strmrdr]

long lgf 82%, low 34 crown 41 pavilion

 

[diamondsrock]

does shorter lgf correspond to more fire and longer lgf correspond to more brilliance?

 

[strmrdr]

Date: 10/29/2005 10:30:28 AM
Author: diamondsrock
does shorter lgf correspond to more fire and longer lgf correspond to more brilliance?

yes and no.

Short lgf tend to return light as broad flashes of fire.
long lgf tend to return light as smaller flashes of fire and more intense white light.
But the white light can be brought back up by opening up the star facets to a larger size say around 55% to 60%+ vs 50% on the short lgf diamonds.

 

[strmrdr]

also keep in mind that there are 2 different ways of measuring LGF%

http://www.goodoldgold.com/minor_facets.htm

So you need to know which your talking about when discussing them.

When talking about the sarin measurments its lenth and when talking about the diamcalc readings its depth.

I usualy use the sarin measurements when talking about actual diamonds because its what you have available.

 

[strmrdr]

conversion chart:

 

[Rhino]

Everything strmrdr has been saying is right on here. There is one more factor that is a possibility as well.

When you take a diamond into direct lighting (ie, spot lighting, sunlight, etc.) ideal cut diamonds take on a "dark" appearance. Ironically it is in these environments that stones with excessive leakage take on a "brighter" appearance however the flashes of light that come out of an ideal cut in those conditions are way more intense than the non ideal but if you''re not aiming the face of the diamond towards the direct light source the stone can take on a darker appearance in those conditions.

 

[Rhino]

Here are some graphics demonstrating the phenomena. This one is the "dark" appearance observed in strong lighting with the stone not really catching any of the direct light.

 

[Mara]

Or it quite simply could have been a crappy cut!! AGS0 does not necessarily mean that it''s going to be a stellar stone. Especially if it''s an older graded AGS0.

I have pulled plenty of AGS0 stones from other sites before and run them through the HCA and come back with scores like 4 or 5.

You will be able to use the idealscope images on a virtual purchase to gauge light return too.

 

[Rhino]

The same exact stone in sunlight except now you''re observing a direct reflection and refraction of light from within the stone. The stone still has a dark appearance but the strength of fire does a decent job of taking center stage.

 

[Rhino]

Here again is the same stone but in totally different lighting which emphasizes beautifully the metric of brightness.

In this view you can see the arrow shafts (which appear black) however the rest of the diamond is extremely bright.

This particular H&A diamond is cut with 77-78% lower girdles.

 

[strmrdr]

Rhino
You have the angles and star lenth for that one?
is the lgf, depth or lenth?

 

[diamondsrock]

I would love to see a non ideal stone with light leakage under those same conditions to compare.

 

[Garry H (Cut Nut)]

You left out darkness caused by steep deep combinations of crown and pavilion angles guys.
If the AGS 0 was a stone before June this year.

 

[pyramid]

That last one Garry H posted looks like the stone I turned down a few months ago as it just seemed so dark in the centre in daylight conditions. Still waiting to buy a larger stone on the internet

 

[strmrdr]

Date: 10/29/2005 5:43:19 PM
Author: Garry H (Cut Nut)
You left out darkness caused by steep deep combinations of crown and pavilion angles guys.

If the AGS 0 was a stone before June this year.

the poster said triangle/arrow shaped dark areas.
Not a ring of death

but i guess they sorta would qualify as trianges in some combos.
But with no magnification the arrows are more likely.
The ring of death tends to blur together and not as distint a shape in person.

 

[Rhino]

Date: 10/29/2005 4:22:29 PM
Author: diamondsrock
I would love to see a non ideal stone with light leakage under those same conditions to compare.

Upon launch of the new site.

 

[Rhino]

Date: 10/29/2005 3:26:47 PM
Author: strmrdr
Rhino
You have the angles and star lenth for that one?
is the lgf, depth or lenth?

34.42 crown angles
40.79 pavilion angles
55.6% table
63% stars
78.1% lower half lengh
79.8% lower half depth
42.56 upper half angles

The whole kit-n-kaboodle regarding numbers are here. Very cherry.

 

[Rhino]

Date: 10/29/2005 5:43:19 PM
Author: Garry H (Cut Nut)
You left out darkness caused by steep deep combinations of crown and pavilion angles guys.
If the AGS 0 was a stone before June this year.

Another excellent example Garry.

 

[strmrdr]

Date: 10/29/2005 6:37:37 PM
Author: Rhino

Date: 10/29/2005 3:26:47 PM

Author: strmrdr

Rhino

You have the angles and star lenth for that one?

is the lgf, depth or lenth?

34.42 crown angles

40.79 pavilion angles

55.6% table

63% stars

78.1% lower half lengh

79.8% lower half depth

42.56 upper half angles


The whole kit-n-kaboodle regarding numbers are here. Very cherry.

thanks.
link didnt work it didnt like the space in the url.
The diamond is here:
http://www.goodoldgold.com/1_52ct_k_vvs2__h%26a.htm

one of my favorite combos cut wise.