New Mineral Named After GIA’s John Koivula
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 Post subject: Measuring Specific Gravity Without a Hydrostatic Balance
PostPosted: Thu Jan 31, 2019 9:22 pm 
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Hi all,
I came across a webpage that showed how to measure specific gravity without using a hyrdostatic balance and only a small digital scale and a cup of water.

My question is how accurate, if at all, would this method be?

1. Find weight of the stone. (1.98 grams)

2. Zero out the scale and weigh the cup of water by itself, then zero that amount out. (37.18g zeroed to 0g)

3. Dip the stone in the water without touching the bottom or the edges. I use an old guitar string the doesn't measure anything when I dip it in the water alone... (.40g)

4. Divide the weight of the stone by the weight of the submerged stone for the specific gravity. (1.98/.4 = 4.95)

I've come across a number of colored gemstones that read higher than 1.8 on my cheap refractometer, so I'm simply trying to determine cubic zirconia vs zircon if possible.

Thanks in advance for any replies!!!


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 Post subject: Re: Measuring Specific Gravity Without a Hydrostatic Balance
PostPosted: Fri Feb 01, 2019 1:52 pm 
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Quote:
Hi all,
I came across a webpage that showed how to measure specific gravity without using a hyrdostatic balance and only a small digital scale and a cup of water.

My question is how accurate, if at all, would this method be?

1. Find weight of the stone. (1.98 grams)

2. Zero out the scale and weigh the cup of water by itself, then zero that amount out. (37.18g zeroed to 0g)

3. Dip the stone in the water without touching the bottom or the edges. I use an old guitar string the doesn't measure anything when I dip it in the water alone... (.40g)

4. Divide the weight of the stone by the weight of the submerged stone for the specific gravity. (1.98/.4 = 4.95)

I've come across a number of colored gemstones that read higher than 1.8 on my cheap refractometer, so I'm simply trying to determine cubic zirconia vs zircon if possible.

Thanks in advance for any replies!!!


I'm sure you could test this on your own with some known samples.
Try it with quartz, fluorite, synthetic corundum and report back.
Good luck!

Sidebar:
Cubic Zirconia is a simple separation from zircon.

Zircon is doubly refractive, profoundly doubly refractive when viewed with magnification.
Image

If you have a hand held spectroscope like an OPL, zircon is also easily identifiable.
Image


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 Post subject: Re: Measuring Specific Gravity Without a Hydrostatic Balance
PostPosted: Fri Feb 01, 2019 4:02 pm 
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Location: Pine City, NY and Dothan, AL
See "Kitchen Counter Rock and Gem ID: Specific Gravity" by Sue Lichtenberger, in the December 2015 issue of the USFG Newsletter.


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 Post subject: Re: Measuring Specific Gravity Without a Hydrostatic Balance
PostPosted: Fri Feb 01, 2019 4:09 pm 
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Tons of good stuff in that Newsletter.
Page 73 for the article listed above.
Direct link:
https://usfacetersguild.org/wp-content/ ... letter.pdf



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 Post subject: Re: Measuring Specific Gravity Without a Hydrostatic Balance
PostPosted: Sat Feb 02, 2019 6:55 pm 
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Thanks for the info. I don't have a spectroscope, but I'm thinking of purchasing one...I have trouble with single and double refraction still, need to do more reading...


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