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 Post subject: surface diffused shots
PostPosted: Tue May 05, 2009 3:02 pm 
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Hi folks,

i’ve wrote another little article for the Preziosa magazine. This one was on corundum surface diffusion (same ol’ stuff, I know, but the article is goldsmith-oriented…).
I added some pics to the article, maybe for some gemmo-newbie those could be useful so i decided to post them. Let’s go:
Here we have a group enjoying a swim in the methilene iodide. for newbies: stones that clearly shows color on the whole surface are diffused, others not.

Image

Same here, a comparison between a diffused (A) and not diffused (B) in immersion

Image

And in direct light

Image

This trio is quite interesting: same scene under different illumination to show a cavity in a diffused sapphire. Oxides used for diffusion entered the cavity and remained there after the polishing.
From left to right:
1)Direct/reflected light: the partially filled cavity is clearly visible and the oxides relics too.
2)direct/darkfield combined light: here a more blue colored zone starting to be visible
3) darkfield light: here the blue surrounding the cavity is clearly visible, oxides inside the cavity diffused the color around it

Image

Here we have a Kanchanaburi diffused sapphire in immersion. The oxides entered inside the stone by the healed fissure reaching the stone surface causing a diffusion around the fissure. Note the step cut pavillion facettes of different color intensity. This was caused by the cutter who has removed too much “color” there.

Image

Particular, darkfield illumination

Image

Another example of the same phenomenon, darkfield illumination

Image

Here we have another one in immersion. Note the typical color concentration on the rims and the different intensity of color between facets.

Image

At last the thin section shows the depth reached by the color.

Image

Enjoy!
Ciao
alberto

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Last edited by Alberto on Wed May 06, 2009 10:04 am, edited 1 time in total.

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PostPosted: Tue May 05, 2009 4:48 pm 
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A great refresher for some of us! Thanks, Alberto :D

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PostPosted: Tue May 05, 2009 5:05 pm 
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You do nice work, Alberto. :)


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PostPosted: Tue May 05, 2009 11:27 pm 
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Well Done Alberto.
Very nice work indeed. It's truly amazing how many in the business are oblivious at how to detect this treatment.

Thanks,
Bear


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PostPosted: Wed May 06, 2009 12:42 am 
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Well done!


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PostPosted: Wed May 06, 2009 2:21 pm 
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A picture's worth a thousand words

very nice


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PostPosted: Wed May 06, 2009 10:39 pm 
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Wow - thank you.

It's great to be able to see so clearly what's discussed by the experts.

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PostPosted: Thu May 07, 2009 3:37 pm 
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Thank you Alberto.

-BF


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PostPosted: Fri May 08, 2009 12:05 pm 
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impressive and professional, thank you Alberto. =D>


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PostPosted: Sat May 09, 2009 3:38 am 
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Thank you all for the kind comments.
i'm wondering if someone of you could suggest a source for a "cheap" sample of surface diffused ruby to add to my collection of synt&treated.
for what i know they're relatively difficult to obtain due to problems related to the chromium diffusion.
neverthless i saw some of them years ago. my gemmo mentore has a nice one sample with the pavillion leaved untouched after the process with the "crust" sticked. 8)
ciao e grazie
alberto

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Last edited by Alberto on Sat May 09, 2009 12:43 pm, edited 1 time in total.

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PostPosted: Sat May 09, 2009 8:10 am 
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Thank you Alberto. :D


Mr calloway


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PostPosted: Sat May 09, 2009 1:14 pm 
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Alberto wrote:
i'm wondering if someone of you could suggest a source for a "cheap" sample of surface diffused ruby to add to my collection of synt&treated.


Sorry, I can't help you with a source. However, if you do find some, what are you going to call them. They aren't rubies. They were made from yellow sapphires and I believe the GIA christened them "Diffusion Treated Natural Corundum" :D :D


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PostPosted: Sat May 09, 2009 1:31 pm 
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Hi Dr. Hanneman

maybe this is the reason why i couldn't find any, i call them with the wrong name! Since now i'm starting to ask for "red diffusion treated corundum".
thank you.
ciao
alberto

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PostPosted: Sat May 09, 2009 1:33 pm 
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thanks Alberto! What a great overview.

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PostPosted: Tue Mar 16, 2010 1:05 am 
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Hi Alberto,

the pics are amazing, i know it's a year old topic but i had to say it.

I wanted to know if i could use your photos because im building a folder for the teacher at my ancient jewellery school for when he teaches gems property. I helped him last time when he did a lab but now im really busy.
Just asking by respect, thanks.

My regards

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