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G&G eBrief Brainteser https://www.gemologyonline.com/Forum/phpBB2/viewtopic.php?f=19&t=14507 |
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Author: | Barbra Voltaire, FGG [ Mon Sep 05, 2011 3:41 pm ] |
Post subject: | G&G eBrief Brainteser |
I clicked on the link we have on the left for G&G eBriefs and stumbled on this Brainteaser from April. I was surprised (in an really positive way) that it incorporated Visual Optics. Check this out: Nite Light What is it? Photo by Robert Weldon And tell us why you think so. |
Author: | Kerensky [ Mon Sep 05, 2011 3:54 pm ] |
Post subject: | Re: G&G eBrief Brainteser |
Rhodonite. Dichroic colours (diagnostic?) High(-ish) RIs Moderate birefringence (so not Rhodochrosite and, anyway, the colour is 'off') Nice stone.... please may I have it |
Author: | Barbra Voltaire, FGG [ Mon Sep 05, 2011 4:01 pm ] |
Post subject: | Re: G&G eBrief Brainteser |
Gee I'm glad this wasn't a prize winning quiz. It would have been pretty boring. I actually think it was the presence of cleavage which separates it from other possibilities. |
Author: | Stonebender [ Mon Sep 05, 2011 4:02 pm ] |
Post subject: | Re: G&G eBrief Brainteser |
Rhodonite? It might also be Rhodochrosite...? I've seen Rhodo's that color. High RI, moderate birefringence , brownish-red pleochroism, typically showing cleavage planes inside of stone. Just a slightly educated guess from a new GIA student! |
Author: | Kerensky [ Mon Sep 05, 2011 4:15 pm ] |
Post subject: | Re: G&G eBrief Brainteser |
Stonebender wrote: Rhodonite? It might also be Rhodochrosite...? I've seen Rhodo's that color. High RI, moderate birefringence , brownish-red pleochroism, typically showing cleavage planes inside of stone. Just a slightly educated guess from a new GIA student! Well, my references give a very large biref and, working on memory of the small number of each I've actually *viewed* the colour split under the dichroscope is right for Rhodonite but not Rhodochrosite. Others who have seen more may feel differently. But it's the biref that's the Rhodochrosite 'killer' I think. |
Author: | Barbra Voltaire, FGG [ Mon Sep 05, 2011 4:17 pm ] |
Post subject: | Re: G&G eBrief Brainteser |
Refractive Index of rhodochrosite is moderate: 1.680-1880 Birefringence is quite high: 0.020 But, indeed, it DOES occur in that color and has perfect cleavage. BUT, RI and Birefringence knock it out of the competition. |
Author: | Stonebender [ Mon Sep 05, 2011 4:20 pm ] |
Post subject: | Re: G&G eBrief Brainteser |
Kerensky wrote: Stonebender wrote: Rhodonite? It might also be Rhodochrosite...? I've seen Rhodo's that color. High RI, moderate birefringence , brownish-red pleochroism, typically showing cleavage planes inside of stone. Just a slightly educated guess from a new GIA student! Well, my references give a very large biref and, working on memory of the small number of each I've actually *viewed* the colour split under the dichroscope is right for Rhodonite but not Rhodochrosite. Others who have seen more may feel differently. But it's the biref that's the Rhodochrosite 'killer' I think. Hmm, I KNOW you knock me out of the park when it comes to this stuff, but I have to say my guess wasn't too bad for an amateur working from memory. |
Author: | Kerensky [ Mon Sep 05, 2011 4:30 pm ] |
Post subject: | Re: G&G eBrief Brainteser |
Trust me.... it's me that's the amateur |
Author: | Barbra Voltaire, FGG [ Mon Sep 05, 2011 4:57 pm ] |
Post subject: | Re: G&G eBrief Brainteser |
Wanna do another? Here is the link to the G&G Brief page Here is a copy of that page: I hope you are all reading these briefs when they become available. They are an excellent source for cutting edge Gem News. |
Author: | Kerensky [ Mon Sep 05, 2011 4:59 pm ] |
Post subject: | Re: G&G eBrief Brainteser |
Moldavite? Czech it out |
Author: | Jason [ Mon Sep 05, 2011 5:01 pm ] |
Post subject: | Re: G&G eBrief Brainteser |
Looks like gas bubbles. Isotropic. Czech republic. Could it be moldavite? |
Author: | George Sharen [ Mon Sep 05, 2011 9:12 pm ] |
Post subject: | Re: G&G eBrief Brainteser |
oh welll a little late with my guess ... but yes moldavite ... George |
Author: | roshanravan [ Tue Sep 06, 2011 12:49 am ] |
Post subject: | Re: G&G eBrief Brainteser |
here is another one http://app.e2ma.net/campaign/1401417.26 ... rainteaser Name That Inclusion! Attachment: e1254776416.jpg [ 42.2 KiB | Viewed 5624 times ] Nature has fashioned an image in this diamond better than any laser could. What is this inclusion? |
Author: | Stonebender [ Tue Sep 06, 2011 3:55 am ] |
Post subject: | Re: G&G eBrief Brainteser |
Some sort of radiation stain? |
Author: | Kerensky [ Tue Sep 06, 2011 5:43 am ] |
Post subject: | Re: G&G eBrief Brainteser |
Hmmm.... if it's an inclusion it beats me. My guess is that it is an artefact - an optical illusion, if you prefer. But, if that is so, I don't know what it is that is being multiple-reflected. |
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