What is "shimmering"

[luvnlife]

I read on here that (paraphrasing) if concerned about clarity/cloudy issue, to turn diamond and see if it shimmers(?) and to use dishwashing liquid?

What does that mean?

Thanks !

 

[luvnlife]

Calling John Pollard -- help please!

On the subject of cloud inclusions affecting light return or sparkle you stated on a post as follows:

"We all counsel caution, especially in the sight-unseen market, but we should not blow this out of proportion. Grade setting clouds in SI stones do not always hinder performance. Remember that clouds are just clusters of pinpoints. Some are denser than others. If the cloud is large but spread out it may be setting the grade but is not any kind of optical issue… If the pinpoints are especially dense an experienced grader knows what to look for. Gemologists go much farther than 10X in a thorough analysis (as do graders in the lab when plotting). Simple use of darkfield and diffused lighting + water/detergent on the diamond reveals an awful lot. One basic test is to turn the diamond and check for a telltale ‘shimmer,’ which is a sign that optical performance is impacted. In any event it is a stone by stone call, to be made by an expert in-person."

What is darkfield?
What is the telltale shimmer?
What is this test with the detergent? And if the stone is eye clean and doesn't exhibit cloudiness except when taking a picture close up, macro, (magnified) does the diamond suffer in your opinion?


Also, the only other spot I notice anything perhaps is in incandescent light from above only in room at night.

 

[luvnlife]

Under comments it says: additional twinning wisps, clouds, pinpoints, surface graining are not shown.

It DOES NOT SAY: grade is based on clouds

 

[TC1987]

http://www.goodoldgold.com/4cs/clarity/
http://www.goodoldgold.com/4Cs/Clarity/InclusionGallery/

I presume that "shimmering" means that the crystals of the cloud are glittering and reflecting light. If there were no crystals or inclusions, you'd have a totally transparent diamond, but with crystals you lose that completely transparent look.

Some inclusions can hide if you look at the diamond face-up and are perpendicular to the table facet. But tilt it and move it around a bit and you may see inclusions.

Twinning wisps and especially graining can have objectionable tint or color, like perhaps brown.

 

[John P]

Calling John Pollard -- help please!

On the subject of cloud inclusions affecting light return or sparkle you stated on a post as follows:

"We all counsel caution, especially in the sight-unseen market, but we should not blow this out of proportion. Grade setting clouds in SI stones do not always hinder performance. Remember that clouds are just clusters of pinpoints. Some are denser than others. If the cloud is large but spread out it may be setting the grade but is not any kind of optical issue… If the pinpoints are especially dense an experienced grader knows what to look for. Gemologists go much farther than 10X in a thorough analysis (as do graders in the lab when plotting). Simple use of darkfield and diffused lighting + water/detergent on the diamond reveals an awful lot. One basic test is to turn the diamond and check for a telltale ‘shimmer,’ which is a sign that optical performance is impacted. In any event it is a stone by stone call, to be made by an expert in-person."

What is darkfield?
What is the telltale shimmer?
What is this test with the detergent? And if the stone is eye clean and doesn't exhibit cloudiness except when taking a picture close up, macro, (magnified) does the diamond suffer in your opinion?


Also, the only other spot I notice anything perhaps is in incandescent light from above only in room at night.

Hello luvnlife.

My quote above was referring to gemological microscopy used by diamond graders. Here are direct answers:

* Darkfield illumination lights the diamond's body from the sides. Since the lenses do not gather direct light the inside of the diamond appears brightly illuminated, against a dark background, making clarity characteristics more visible and easier to analyze.

* When a cloud is dense, or has enough sizable/numerous pinpoints, a gemologist may turn the diamond to see if those particles are inhibiting light paths. If a flickering or 'shimmering' appears in that area (like light reflecting from water) it's a sign that some light entering the crown is blocked from its proper path and not returning to the viewer's eye. While best seen in darkfield, I also use diffused and point-source lighting - but I'm a big nerd. If the blockage is severe enough it can visibly inhibit performance.

*Wet grading is common. Using a tiny brush or sponge, we apply distilled water with a few drops of detergent added (the detergent helps stop the water from beading) to the diamond's surface. This removes fingerprints, grease and dust, and leaves a clear window into the diamond so we don't confuse surface detritus for blemishes.

And if the stone is eye clean and doesn't exhibit cloudiness except when taking a picture close up, macro, (magnified) does the diamond suffer in your opinion? ... Also, the only other spot I notice anything perhaps is in incandescent light from above only in room at night.

I can't say without examining the specific diamond. If light path blockage occurs mainly on the pavilion-side (after initial reflection) you won't see evidence from the top. But the effect, and the characteristics causing it, becomes more eye-visible as density/severity increases. The SI diamonds I've seen with eye-visible issues are few and far-between. Those I have seen with GIA reports generally included the comment "Clarity grade based on clouds not shown." The comment you noted - "Additional clouds and pinpoints not shown" - means that whatever is not-shown was judged to be a non-factor.

In the interest of fair-reporting a gemologist friend challenged me on this "non-factor" comment, since it has been my position for years. He showed me a 1.50 GIA SI with "Additional clouds not shown," where clouds hovered throughout the entire diamond and did indeed impact face-up performance. The amusing things was that he held onto the diamond for over a year, just waiting for us to get together so he could "show me!" If you know diamond dealers that's kind of extreme. I asked if he'd ever seen another - he said no.

Garry Holloway may have more to add. I wager he's seen more SI cloud/wisp/grained diamonds with issues than I have. But this may be because he's in Australia and all the naughty diamonds get sent there.

The above is offered in the spirit of information. I will say again, when strictly graded, such SI examples are few and far-between in my experience. If your diamond was analyzed by a thorough gemologist you're very likely protected. And if you and your friends don't see areas of reduced brightness in diffused light or dead scintillation zones in point-source lighting (your favorite places for generating sparkle) I would not obsess over it.

I do applaud you for thoroughness. I take the same position on any diamond I assess, as if I were shopping for myself.

 

[luvnlife]

Hi John,

Thank you so much for your in-depth reply. I wasn't sure if okay to put cert online but if you want to see it I could. The plot shows twinning wisps, and states as I have mentioned above.

I went to an appraiser and under a very quick exam --knowing it wasn't for insurance purposes-- (I wanted her to check if she saw any red flags) was told that it was probably my setting on the camera I used and said there was no cloudiness and it was a very pretty stone. That I should have no worries. she said that the other stone was easier to photograph due to the depth of stone.

To refresh your memory because you have responded to my concerns before -- I was the gal that did the upgrade from the deeper gia xxx to the 40.8, 34, 58, 60

My question is, is it possible for the appraiser to make that positive assumption in a very short amount of time? She knew I had a concern but I didn't tell her what it was. If a picture taken by camera looks cloudy, and not to the eye, is it possibly not a problem? Maybe it is the camera? I did what you said and the stone looks very bright, and shows great sparkle under certain lights , but how much is hard to tell compared to other stones cut similarly. I don't have that accessibility. I get concerned in the incandescent lighting as it doesn't seem to do much there but then again I don't remember what my other stone did there either.

I'm not sure if it is shimmering though as I now have a much shallower stone so not sure about that. I almost think it does but it would be the entire face of the stone then, not just a certain section.

It seems my new stone acts a lot differently than my old stone.
Thanks so much for your help!

 

[John P]

Hi John,

Thank you so much for your in-depth reply. I wasn't sure if okay to put cert online but if you want to see it I could. The plot shows twinning wisps, and states as I have mentioned above.

I went to an appraiser and under a very quick exam --knowing it wasn't for insurance purposes-- (I wanted her to check if she saw any red flags) was told that it was probably my setting on the camera I used and said there was no cloudiness and it was a very pretty stone. That I should have no worries. she said that the other stone was easier to photograph due to the depth of stone.

To refresh your memory because you have responded to my concerns before -- I was the gal that did the upgrade from the deeper gia xxx to the 40.8, 34, 58, 60

My question is, is it possible for the appraiser to make that positive assumption in a very short amount of time? She knew I had a concern but I didn't tell her what it was. If a picture taken by camera looks cloudy, and not to the eye, is it possibly not a problem? Maybe it is the camera? I did what you said and the stone looks very bright, and shows great sparkle under certain lights , but how much is hard to tell compared to other stones cut similarly. I don't have that accessibility. I get concerned in the incandescent lighting as it doesn't seem to do much there but then again I don't remember what my other stone did there either. Thanks so much!

Hi luvnlife. You're very welcome and it's nice to dialogue with you again.

Even a high-end camera with a clean macro lens has limitations in the way it transposes three-dimensional body depth into a flat image. If your appraiser used a microscope, or is expert with a triplet loupe, she was able to take the examination far beyond the abilities of a camera. A professional's assurances of no cloudiness and no worries probably means a lot more than whatever input-from-afar we can provide here.

As a general rule twinning wisps don't occlude large areas of the diamond as clouds may. Because they are structural distortions, wisps are typically easier to see and account-for than, say, a thin cloud of transparent pinpoints which spans the diamond.

RE Incandescent lighting: It's not surprising. When only a few bulbs light an area anyone's diamond can look pretty flat. In my garage I have my last incandescent bulb. It's single and it's bare. It's also very bright but my super-duper-cut diamond looks terribly dark in there. This is because my diamond is "looking" for light in most of the hemisphere, but only finding a single source that is (relatively) weak and may be further obstructed by my head or body.

Consider that our sun is the brightest possible incandescent light in our world, but it only sub-tends light at about one-half a degree. This means that, in the entire 180-degree hemisphere, the sun is one tiny point light source occupying only 1/360 of the total area in which the diamond "looks" for light. It is a ridiculously bright source - so it generates crazy sparkle - but even the insides of well-cut diamonds can go dark when you're standing out in sunlight.

Try this. Find a place that has a ton of bright incandescent lighting and mirrors. When you multiply the light sources your diamond can find more of them - and give back what it receives. I swear my wife spends extra time in our master bathroom getting ready because it's a great zone for her bling to sing.

More on that, if you're interested, in this thread:
https://www.pricescope.com/community/threads/darkness-in-ideal-cut-diamonds-revisited.150108/

Aside from all of this, how are you enjoying the upgraded diamond?

 

[luvnlife]

Thanks, John!

I am enjoying my new diamond, albeit cautiously! (I upgraded color) It looks fabulous in certain lighting and the reason I have had concerns is because of the not so great appearance in incandescent lighting, and of course the cloudy look in the photos. Also, I think the problem, good or bad, is that I am used to basically looking into the diamond and now I don't have that depth, it's just the facets, and when there is no beam of shining light you see a duller view(?) I do hope that is the better alternative! The other diamond seemed to have more white flash and this diamond has more colored flash which I like better. I also think it is a much prettier stone in most lighting.

I really love the contrast/splintery look of this stone. Even though there are arrows, although you don't really ever see them, the stone shows a more splintery look as opposed to chunky perhaps due to the twinning lines.