Joined: Fri May 12, 2006 11:24 am Posts: 7523 Location: Rome, Italy
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.
Same here, a comparison between a diffused (A) and not diffused (B) in immersion
And in direct light
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
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.
Particular, darkfield illumination
Another example of the same phenomenon, darkfield illumination
Here we have another one in immersion. Note the typical color concentration on the rims and the different intensity of color between facets.
At last the thin section shows the depth reached by the color.
Joined: Fri May 12, 2006 11:24 am Posts: 7523 Location: Rome, Italy
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.
ciao e grazie
alberto
Joined: Mon May 14, 2007 11:00 am Posts: 1133 Location: Monterey, CA
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"
Joined: Fri May 12, 2006 11:24 am Posts: 7523 Location: Rome, Italy
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
Joined: Thu Dec 03, 2009 3:31 am Posts: 228 Location: Montreal, Quebec, Canada
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.
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