Post subject: Can Anyone Help with This transparent Stone
Posted: Sun Feb 14, 2021 11:56 am
Established Member
Joined: Sun Feb 07, 2021 4:01 pm Posts: 26
Hi First of all thanks for reading this post
Can anyone help in identifying this gemstone
i am new to gemology but very keen to learn
here is what ive got so far
Magnetism = No or my magnet is weak Specific Gravity= 2.53 Pleochroism= None chelsea filter reaction = goes transparent green UV = no reaction RI ( using digital refractometer) =1.385 - 1.545 = -0.16
Any help would be much appreciated
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Post subject: Re: Can Anyone Help with This transparent Stone
Posted: Sun Feb 14, 2021 8:11 pm
Gold Member
Joined: Tue Apr 05, 2016 7:58 pm Posts: 1424 Location: San Marcos, CA
1bwana1 wrote:
I hope you are noticing how useless the digital refractive index number are. Thank that machine out and crush it with your car.
LOL. While your at it, give it company with the whatever the SG readings are coming from. I guess I shouldn't say that here as the SG isnt bad if it is quartz. But not to be to critical the photos are better than most, and it looks like some of the double terminated petroleum quartz crystals I have seen.
Post subject: Re: Can Anyone Help with This transparent Stone
Posted: Thu Feb 18, 2021 12:03 am
Site Admin
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21600 Location: San Francisco
As I mentioned in another one of your "Can anyone help" posts, I pointed out that digital reflectometers are not digital refractometers. Furthermore, they are very unreliable.
Whenever someone mentions the Chelsea Filter, I think of Tim Spauwen's (one of our original MODS) instructions for proper use of the Chelsea Filter.
Tim Spauwen wrote:
Find a bright window. Open it up. Throw filter outside. Close window.
Post subject: Re: Can Anyone Help with This transparent Stone
Posted: Thu Feb 18, 2021 2:14 pm
Gold Member
Joined: Tue Apr 05, 2016 7:58 pm Posts: 1424 Location: San Marcos, CA
Not a complete waste, can be used to quickly isolate certain types of light blue gems in larger parcels. But not an everyday go-to for individual stone testing. I may be wrong but was intentionally for identifying dye in Jade?
Post subject: Re: Can Anyone Help with This transparent Stone
Posted: Thu Feb 18, 2021 3:46 pm
Site Admin
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21600 Location: San Francisco
As Dr. Hanneman used to say with some regularity, "Filters are confirmative, not determinative."
That means, that if you have a parcel of stones which are supposed to be aquamarine and you view it with the Chelsea and all appear the same, that will not determine that you have aqua, it will simply indicate that it is likely all your stones are compositionally the same.
If one jumps out as a different color with the filter, it is likely that that stone is not the same as the others.
But, you have not determined the identity of anything, just confirmed that several are likely the same and one is not.
Make sense?
This is a tool which is useful in lapidary circles, but I would not recommend it for gemological use.
Post subject: Re: Can Anyone Help with This transparent Stone
Posted: Thu Feb 18, 2021 3:51 pm
Site Admin
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21600 Location: San Francisco
Quote:
I may be wrong but was intentionally for identifying dye in Jade?
Perhaps at one point, before common bleaching and impregnation was widely used. I would not use it on contemporary examples of jadeite (or any examples frankly). For treatment verification we can currently only trust Raman and FTIR for jadeite..
Post subject: Re: Can Anyone Help with This transparent Stone
Posted: Thu Feb 18, 2021 4:13 pm
Gold Member
Joined: Tue Apr 05, 2016 7:58 pm Posts: 1424 Location: San Marcos, CA
Thanks Barbra well said in the gemological way. We used it in this sense more of a in the field quickly to separate for further testing, or to see if the parcels were tainted or an untrustworthy source.
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