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 Post subject: Tools for Specific Gravity
PostPosted: Thu Oct 19, 2006 9:54 am 
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I'm thinking about buying a tool for determining SG. I haven't really needed one yet, simple heft by feel has been sufficient. But now I'm faced wtih separating out some mixed gem rough and SG is a major clue to ID in such cases.

I have been reading about the Hanneman Direct Reading Specific Gravity Balance ( http://www.mineralab.com/Hanneman.html ). It seems to be a really great tool that is relatively inexpensive. Has anyone tried one? Are they accurate?

My other option is to get a more traditional SG set up for a scale. (e.g. http://www.mineralab.com/Scale.htm ). Are there any advantages to the traditional method over the Hanneman Direct Read?

(note: I'm only using the mineralab.com site as a convenient example; I haven't done any business with them.)

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PostPosted: Thu Oct 19, 2006 9:59 am 
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As much as I revere Dr Hanneman, I must report, I ordered his scale, perhaps 15-20 years ago and couldn't sort it out for the life of me. Finally I just threw the components away.

I own the latter scale, use it routinely and have excellent results.
I actually, just recently made a short (2 minute) video on determining SG and used the gizmo from Mineral Lab with my Mettler for perfect results.
I think Snizzy uses this unit with a small protable Tanita Scale and gets great results as well.


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PostPosted: Thu Oct 19, 2006 11:16 am 
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This raises some interesting possibilities for me. I have a fully-assembled new Hanneman balance that works fine but it's in a box because I don't have space for it on my bench. I'd sell it for less than the Mineralab price.

Due to a tragedy of errors I also have a brand new unused Mineralab Universal Specific Gravity Kit for a pocket-size carat scale. I ordered it before leaving on a trip and when I returned my precious little scale had gone to Digital Heaven. Long story short, my new scale is bench-sized and can't accommodate that version. Any purchase/swap offers out there?

Rick Martin


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PostPosted: Thu Oct 19, 2006 12:17 pm 
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Barbara -- was the scale you ordered the same as the one currently offered at Mineralab? Did the design change since you tried it?

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PostPosted: Thu Oct 19, 2006 12:22 pm 
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Hi,

I can build a McGuiver/A-team -style SG kit in 30 seconds, no reason why you can't.


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PostPosted: Thu Oct 19, 2006 12:36 pm 
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Thanks for the vote of confidence Doos . I'd love to see you do that in 30 seconds! :D

I may just try it -- but unfortunately, whenever I've tired the do-it-yourself thing in the past, I've ended up buying the professional tool later anyway.

peter

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PostPosted: Thu Oct 19, 2006 1:55 pm 
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Then you should probably make ROM an offer :wink:


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PostPosted: Thu Oct 19, 2006 2:04 pm 
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The SG Kit from Mineral Lab is the same as it always has been. It's a good unit. What kind of scale are you going to use it with? Make sure that the bottom of the Specific Gravity Kit is the proper sive, otherwise you won't be able to use it.
After you know its the right size, buy it from ROM. It doesn't have any component that could really be damaged or misused.


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PostPosted: Thu Oct 19, 2006 2:09 pm 
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Barbra Voltaire wrote:
The SG Kit from Mineral Lab is the same as it always has been. It's a good unit. What kind of scale are you going to use it with?


At the moment, I have a little Dendritics 50ct scale. From what I read, it should be sufficient for small stuff (<10ct). A scale upgrade is in the not-so-distant future too....

peter

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PostPosted: Thu Oct 19, 2006 4:30 pm 
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I meant, take a look at the paltform for weighing on the scale because the SG kit comes in 2 different sizes. I got the larger one which fits on my Mettler, but it's far too large for my Tanita.

Am I making sense?


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PostPosted: Thu Oct 19, 2006 5:36 pm 
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Barbra Voltaire wrote:
I meant, take a look at the paltform for weighing on the scale because the SG kit comes in 2 different sizes. I got the larger one which fits on my Mettler, but it's far too large for my Tanita.

Am I making sense?


Yes, I understood you. I measured things and then got sidetracked into reading about the min. weight requirements.

The SG unit bottom should just fit the pan on my little scale.

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 Post subject: Using Hanneman Direct SG Reading Balance
PostPosted: Fri Nov 17, 2006 10:30 pm 
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This is my first post, so let me introduce myself. I am a gemmology student at the Canadian Gemmological Association www.canadiangemmological.com. I am in the second year of the part-time course and have found these forums to be very interesting and informative reading.

Just yesterday I used the Hanneman Direct Reading SG balance for the first time. It is a simpler model than that sold at Mineralab, and uses a piece of cardboard with a pencil line for the zero point. Without using much care, I determined the SG of a 10ct tourmaline at 3.15 (actual SG is 3.05 for this stone).

The instructor stated that with proper care and practice, she is able to accurately determine the SG of stones as small as 0.02ct.

BTW - The scale was purchased as a kit a number of years ago from Hanneman for $15.


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PostPosted: Sat Nov 18, 2006 12:37 am 
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looks like were all over the board with this one.. there are several pieces of equipment that really put the nail in the coffin when determining species of gems, and determining sg is one of them.. get the best on you can afford, or get one you can afford now with the plan of replacing it when you can buy a very good one.. . the one you have specified says it will do .75 carots accuratly.. that would not be good for diamonds or small cut gems in my way of thinking.. but it depends on what your doing.. some of the small accurate scales wont do large rough pieces.. i use a tripple beam balance for large gold necklasses and the like.. .. i also use the large desk scale like the acculab/ohous that goes to .001 gram and sg kit to match and that is veeery nice!!! what you need to pay attention to is how many grams you want to be able to weigh.. the electrical scales have a maximum weight you can do, or it will do damage to the scale.. dave..


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