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 Post subject: Is there a low tech way to tell glass from natural quartz?
PostPosted: Wed Apr 09, 2014 1:31 am 
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Trying to figure out some beads I just purchased... I looked at the pictures carefully on ebay (seller is ek beads), they did not have that all exactly the same shape some had, I thought it might make it more likely they were cut not molded...
but they are a lot more clear than any of my other (sold as) natural quartz (which could just mean my other beads are not the same quality?) and the finish looks odd...

looking at the all, I found a few that looked a little less clear but hard to tell if it is just in the finish....
I've contacted sellers and asked and had some admit their beads are glass... ("Natural glass quartz"), these sellers said they were natural, now say "no one has thought they were glass before..."

Is there a way to tell for certain, lacking good equipment?

should I find a local lapidary club?


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 Post subject: Re: Is there a low tech way to tell glass from natural quart
PostPosted: Wed Apr 09, 2014 8:26 am 
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"Natural glass quartz"? I don't even know what that means.

Quartz is significantly harder than glass, and will scratch it.

Do find a local lapidary club. You'll not only get help, but meet some interesting people who do interesting things.


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 Post subject: Re: Is there a low tech way to tell glass from natural quart
PostPosted: Wed Apr 09, 2014 9:28 am 
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Get a loupe. Look for air bubbles.


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 Post subject: Re: Is there a low tech way to tell glass from natural quart
PostPosted: Wed Apr 09, 2014 1:52 pm 
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Touch it to your lip. Quartz is cold, glass is merely cool. This is because quartz has a regular crystal structure which conducts heat well, where glass's internal structure is chaotic and does not conduct well.

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 Post subject: Re: Is there a low tech way to tell glass from natural quart
PostPosted: Mon Apr 14, 2014 10:00 pm 
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Could it also be figured out by weight? How much does a cubic centimeter of 'glass' weigh versus a cubic centimeter of quartz?

- George


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 Post subject: Re: Is there a low tech way to tell glass from natural quart
PostPosted: Tue Apr 15, 2014 2:36 pm 
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Glass is usually less dense than quartz (lack of internal structure leads to inefficient use of space, essentially) so a simple SG test would work as well. But it's hard to beat the 'ol lip test for low tech.

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 Post subject: Re: Is there a low tech way to tell glass from natural quart
PostPosted: Tue Apr 15, 2014 3:06 pm 
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buy a refractometer and check RI and double refraction...buy a polariscope to seperate single or double refractive...or learn visual optics and tell single refractive from double refractive that way...this is a gemmology site...we should advocate gemmological practice...visual optics is free...a refractometer doesn't cost that much...a polariscope costs less (or can be made for cheap...especially if you are reselling these beads...you have a responsibility to properly advertise your goods...neither solution is very expensive but you will have to learn how to use the instruments. Only by optically testing the material can we be sure.



just my 2cts


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 Post subject: Re: Is there a low tech way to tell glass from natural quart
PostPosted: Tue Apr 15, 2014 3:57 pm 
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Anyone doing serious business in the trade should be familiar with these important tools. But I think it's probably overkill for differentiating quartz and glass beads. They differ so much in the easy properties that there may not be any need for these optical measurements. A simple hardness test, for instance, would also be another easy way to definitively differentiate them. While they are not high tech, hardness testing, thermal conductivity and SG are all gemological practices of a sort as well.

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 Post subject: Re: Is there a low tech way to tell glass from natural quart
PostPosted: Sun Apr 27, 2014 3:39 am 
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Scarodactyl wrote:
Glass is usually less dense than quartz (lack of internal structure leads to inefficient use of space, essentially) so a simple SG test would work as well. But it's hard to beat the 'ol lip test for low tech.


temperature, I have both quartz and glass, I can give that one a try..

what is the ol lip test?


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 Post subject: Re: Is there a low tech way to tell glass from natural quart
PostPosted: Sun Apr 27, 2014 3:47 am 
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Frank wrote:
buy a refractometer and check RI and double refraction...buy a polariscope to seperate single or double refractive...or learn visual optics and tell single refractive from double refractive that way...this is a gemmology site...we should advocate gemmological practice...visual optics is free...a refractometer doesn't cost that much...a polariscope costs less (or can be made for cheap...especially if you are reselling these beads...you have a responsibility to properly advertise your goods...neither solution is very expensive but you will have to learn how to use the instruments. Only by optically testing the material can we be sure.



just my 2cts


http://www.gemologyproject.com/wiki/ind ... olariscope
potential.... something I could bring to bead faires... would really help


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 Post subject: Re: Is there a low tech way to tell glass from natural quart
PostPosted: Sun Apr 27, 2014 3:48 am 
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Thank you!
all


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