Post subject: Re: Dr. Hanneman's Tips: 2 :Specific Gravity Balance
Posted: Tue Nov 01, 2016 7:16 pm
Valued Contributor
Joined: Fri Nov 01, 2013 3:45 pm Posts: 289
Hello every one,
I realize that the Hanneman specific gravity balance is very nice, cheap and direct to evaluate the specific gravity of a gem. I am interested in that device.
I also read that a lot of gemmologist use digital scale, which is expensive.
Post subject: Re: Dr. Hanneman's Tips: 2 :Specific Gravity Balance
Posted: Tue Nov 01, 2016 7:39 pm
Valued Contributor
Joined: Fri Nov 01, 2013 3:45 pm Posts: 289
Hello Barbra,
Suppose that you weight a gem by placing it on the left. You evaluate the weight on the other side in carat with the little things provided for that.
After, you take off the gem and you put the left side in a little glass filled with water. You place back the gem on the left, in the water. You weight the gem again with the same little things.
After your put your numbers in the equations for the SG. You take the weight en carat in air and you divide it by the difference in your 2 results in carat.
Post subject: Re: Dr. Hanneman's Tips: 2 :Specific Gravity Balance
Posted: Wed Nov 02, 2016 8:14 am
Gemology Online Veteran
Joined: Thu Mar 19, 2015 9:55 am Posts: 543
Hi Brigitte, look at my "Drawings for specific gravity balance" in "Gem Equipment". Yes, it uses a digital balance, but they are getting cheaper by the month! I bought a certified one to 0.0005 carat for just over $40.00 last year.
Maybe the little vintage balance is not precise enough? We can weight at the 0.01 carat.
Alan, thank you for sharing. Interesting and helpful, indeed. The chart temperature/precision is helpful also. I wonder where you found a so precise balance at that price. Is the shipping included in that price? I suppose it is in USA dollars.
Post subject: Re: Dr. Hanneman's Tips: 2 :Specific Gravity Balance
Posted: Wed Nov 02, 2016 11:38 am
Gold Member
Joined: Wed Jan 23, 2013 5:29 pm Posts: 1047 Location: Paris
I think the device will be complicated to build with a two pan balance. Furthermore, as is written in the link :
"The two-pan scales are the most time-consuming scales to use though some jewelry stores still have them. But they are rarely used for determining SG of stones, mostly because the counterweights are generally too big to be of any help. Besides, they really need to be calibrated every few years."
All in all, for more precision and easiness you had better use a digital scale.
Post subject: Re: Dr. Hanneman's Tips: 2 :Specific Gravity Balance
Posted: Wed Nov 02, 2016 12:53 pm
Gemology Online Veteran
Joined: Thu Mar 19, 2015 9:55 am Posts: 543
Sorry Brigitte, a slip of the decimal point, my balance reads to 0.005 carats, or 1 milligram. A two pan balance can be used, by having a bridge and basket over one pan, but as ISI says, single pan is easier.
Post subject: Re: Dr. Hanneman's Tips: 2 :Specific Gravity Balance
Posted: Wed Nov 23, 2016 5:23 am
Gemology Online Veteran
Joined: Thu Mar 19, 2015 9:55 am Posts: 543
Hi Brigitte, yes, the balance is performing well, not only accurate, but repeatable and it holds its zero. I bought it from Kern, a crack German instrument firm (Google them). At the time it was very reasonable, but the pound was up against the euro and we have the benefit of no duties in Europe. At the moment the dollar is way down against the Euro and US duties can be eyewatering, so check before ordering.
Post subject: Re: Dr. Hanneman's Tips: 2 :Specific Gravity Balance
Posted: Mon Dec 05, 2016 3:45 pm
Gold Member
Joined: Mon May 14, 2007 11:00 am Posts: 1133 Location: Monterey, CA
Brigitte wrote:
Hello every one, I realize that the Hanneman specific gravity balance is very nice, cheap and direct to evaluate the specific gravity of a gem. I am interested in that device. Brigitte
Post subject: Re: Dr. Hanneman's Tips: 2 :Specific Gravity Balance
Posted: Sun Jan 28, 2018 12:31 am
Gold Member
Joined: Tue Jul 02, 2013 9:00 am Posts: 1322 Location: Wylie Texas but in Alaska for a while
Bill Hanneman wrote:
Hold on for just a minute.
That article was written 50 years ago.
Next month, at Tucson, I will be introducing a new approach to density. It is based on relative density, which is simpler, faster, and anyone can make themselves in a few minutes.
Keep you eyes open. I just have to write the instrutions and I have only 10 days.
Did this ever get posted?
I know that we are in the middle of this years show, so everyone is to busy...
It sounded like this was presented at the show.
Are there any videos or copies available of these types of presentations?
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