They call it a refractometer but it is a reflectometer. It can read percent reflectivity or converted refractive index which isn't a bad idea.
It does say Gem Instruments which is a trademark of GIA and when they notice it these people will not be able to sell on ebay until they remove the infringing label.
I think it is still too expensive.
One of our members recently allowed me to examine his Presidium reflectivity meter. They are nicely made and do the same thing for less than $200 end user. They read out in (very) arbitrary units and you calibrate with known stones and compare to a chart which comes with the unit.
I also had occasion to chat with another list member who has the $800 Austrian made "Gemmeter" which has the clever birefringence chart built in.
He hates it. He says it takes 45 minutes of calibration every time he uses it
which defeats the purpose for which he bought it, namely portable quick and easy readings.
Last edited by G4Lab on Sat Jul 28, 2007 8:46 pm, edited 1 time in total.
Joined: Wed Mar 28, 2007 12:35 am Posts: 44 Location: Nepal
Thank to everybody for your comments on this product.I was quite confused whether it is similar with the product discussed on the research topic past Feb this year as "Digital Refractometer - Soliciting Input"
Its link is http://gemologyonline.com/Forum/phpBB2/ ... php?t=2098
Joined: Mon May 14, 2007 11:00 am Posts: 1081 Location: Monterey, CA
Regarding your questions:
With a tolerance of 0.007, you can forget about determining birefringence or even if the stone is singly or doubly refractive.
If it utilizes infrared light, you can forget about getting accurate RI values for highly dispersive stones. Sure, you can "calibrate" it to have diamond read 2.417, but then you will never be able to get strontium titanate to read 2.41.
If you want to identify unknowns with RI below 1.8, get a critical angle refractometer. However if you just want to identify the common diamond simulants, get yourself a "Diamond Eye" which only costs $89.
If your goal is to buy an instrument which will save you time and identify unknowns without requiring any knowledge or effort on your part, save your money and pray for a miracle.
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