I made the mistake of purchasing one of these pieces of junk from mineralab.com. I spoke with the owner, Tim Flanegin, extensively about how well they worked and was assured that it worked well. IT DOESN'T AT ALL I have tried it on around 100 stones and it has given me a reliable reading maybe 5% of the time. And those were only on OTL stones or glass. Immediately after receiving it I complained and was told that it was something I was doing wrong: the stone was dirty, etc. Tim even tried to say that I wasn't using real sapphires once. I wanted it to work out, so he allowed me to trade units. The second one worked the same. I have asked to return it and have even agreed to pay a restocking fee, but he has stopped returning my emails.
Post subject: Re: Gem N Eye III digital refractometer
Posted: Tue Jul 16, 2013 1:23 pm
Site Admin
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
It has been my experience with the reflectometer, (they are not technically refractometers) that they need to be calibrated often.
Using known gems....quartz, synthetic corundum, synthetic flame fusion spinel, one can calibrate these units pretty successfully. Then they will work for the next unknown you test.
Next time you use it, test it with your known gems again. Recalibrate and then recalibrate again.
Post subject: Re: Gem N Eye III digital refractometer
Posted: Tue Jul 16, 2013 3:08 pm
Platinum Member
Joined: Tue Jan 02, 2007 8:20 pm Posts: 2659
I think the Gem N Eye attempts to be "all digital" and is not able to be manually calibrated, as have most previous analog reflectometers.
I have not played with one of these but was immediately suspicious of the unit because it has a digital look up table to suggest the ID of the gemstone. I would run in the other direction from ANY reflectometer that purports to measure birefringence or has a built in look up table. (there is another similar one from Austria that one of our list members a HIGHLY experienced gemologist, had an essentially identical experience with. Bought the unit with high hopes. Lots of BS interactions with the developer. Asked for a refund. Developer goes off the air. )
I would suggest initiating a charge back with your credit card.
Dr. Bill Hannemann's latest model has you check against known stones each time. He has done away with the screwdriver cal adjustment and replaced it with an adjustment knob.
Similarly the Presidium model comes optionally with a set of four or five OTL stones to adjust the calibration against.
Reflectometry is a very twitchy measurement for Gem ID. Dr. Hannemann who has sold as many of these as anyone refers to it as a confirmative rather than determinative measurement. It is really a very weak piece of data and I would never depend on it being accurate. For one thing the measurement of "reflected" light has no way to distinguish between light reflected at the surface of the gemstone (what you are trying to measure) and light that has entered the gemstone and been "retroreflected" by the pavilion. You can try to minimise this by sliding the gem over the measurement port but it is difficult to determine what you are really getting.
Thank you for posting this warning for everyone. I suspected that was the case with that instrument but had not had the opportunity to try it out.
Post subject: Re: Gem N Eye III digital refractometer
Posted: Tue Jul 16, 2013 3:33 pm
Valued Contributor
Joined: Fri May 26, 2006 2:35 pm Posts: 153 Location: Brazil
Hi,
I made the mistake, a few years ago, to buy a gemmeter from a guy living in Germany. The thing is manufactured in Austria. Paid more or less 750 U$. Worst piece of crap I ever bought. You switch the thing on, have to wait a few minutes, then you start calibrating and after 15/20 minutes it is calibrated. Then you can measure a stone or two, and if you switch the thing off, you can start all the procedure again, really getting on my nerves!
Post subject: Re: Gem N Eye III digital refractometer
Posted: Tue Jul 16, 2013 7:51 pm
New to the Forum or The Quiet Type
Joined: Tue Jul 16, 2013 11:15 am Posts: 3
I spent a lot of time calibrating the machine. It has multiple ranges that can be calibrated based on a certain stone. So, say you calibrate Quartz, it adjusts any stone with an RI in the Quartz range by whatever the amount your calibration was. It didn't matter if i calibrated the machine up or down as the machine was way off and not in one direction or another. it just plain doesn't work. And the owner kept telling me that it was my fault because the stone or lens was dirty, but I followed the directions to a "T" because I wanted something easier than a critical angle refractometer
Post subject: Re: Gem N Eye III digital refractometer
Posted: Wed Jul 17, 2013 3:31 pm
Platinum Member
Joined: Tue Jan 02, 2007 8:20 pm Posts: 2659
Definitely not your fault. Your experience is 100% consistent with everybody elses. Thank you for taking the time to blow the whistle on yet another piece of junque.
Post subject: Re: Gem N Eye III digital refractometer
Posted: Sat Jul 20, 2013 6:13 pm
Valued Contributor
Joined: Sun Jul 15, 2012 6:29 pm Posts: 321 Location: Los Angeles, CA
G4Lab wrote:
Dr. Hannemann who has sold as many of these as anyone refers to it as a confirmative rather than determinative measurement. It is really a very weak piece of data and I would never depend on it being accurate.
Post subject: Re: Gem N Eye III digital refractometer
Posted: Thu Jul 09, 2020 8:09 pm
New to the Forum or The Quiet Type
Joined: Thu Jul 09, 2020 9:13 am Posts: 1
I have one and have had it for over 2 years. It is very accurate I've verified and identified (which takes many inputs/different tests to do) with the gem n eye 3.
The more jeweler grade your stone is the easier the machine tests. Tim gives you two test stones, then you can calibrate the machine manually based off known or certified gem quality stones.
It takes patience but if you are receiving stones from overseas their typically not fake but many of them are misidentified. If your machine is reading the same thing over and over you must consider a good possibility it was not accurate in someone's assumption. To identify you will need atleast the conductivity tester, a number one helps for the inputs. I've verified and identified over 50 stones types using this computer with other assisting tests as input into the machine.
For less than optimal stone polishing them must be heavy. Their not all going to test perfectly because they maybe on cusp of other stone identification properties. This is where get a good median(slightly higher or lower) can come into play. Vigilants and patience.
I have for identification hardness test, conductivity, specific gravity scale, calcite pleoclorism scope. A pleoclorism chart comes in handy. These are all the major inputs for the gem-n-eye 3.
Many stones are confused because their conductivity is in the range of glass or another stone.
Post subject: Re: Gem N Eye III digital refractometer
Posted: Sat Aug 08, 2020 7:59 pm
New to the Forum or The Quiet Type
Joined: Tue Jan 21, 2020 7:02 pm Posts: 1
I have one that I usually use it for the high end stones. You do have to make sure you calibrate it and make sure you use the cloth that comes with it to polish the table of your stone before placing it in the unit.
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