Presidium Electronic Refractive Index Meter II

we like it. there is a learning curve in buying a function specific product. the more you know about gemstones, the better your results will be.as far as product creation, and selling, no problems there. fair transaction, prompt service, quality device. too early to tell about the computer connection.. another learning to do. presently, i see it as being a good tool to add to your bag of tricks, in identifying gemstones.the seller is prompt in assisting you with problems, and need guidance. no device out there, that I know of is the all in one device to identifygemstones. portabel,, easy to use. it is worth the price.

I previously entered a review and gave it 4 stars. I only had it a few months at that point. Here it is at the 10 month mark and I'm really unhappy with this product. Angry is a better word. I wasted 100 hours before I found out it needed to be calibrated again. It worked fairly well for six or seven months. But then trouble started. The digital readout, for example, could be (RI) of 1.597. But tested manually the correct reading would be 1.619. That's an insane error. The machine couldn't even get the first decimal place right, let alone the second and third.Now it has to be sent to Singapore to be calibrated. It first has to go to California. They only ship once a month and that's toward the end of the month. And then it takes "seven weeks" to calibrate it in Singapore. I had to pay for shipping to California. It's under warranty, so that's all I have to pay. However, by the time I get it back, the warranty will have expired! If I had to pay for the calibration it would cost about $50, take about 3 months (depending on when it's shipped to CA), and pay about $25.00 for postage. Had I known this upfront, I would never havepurchased the product. Having it work correctly for about 6 months was NOT worth $280!

I sent one of these back because I kept getting erratic measurements with known Moisanite samples. Actually it would many times report RI of 2.42 or 2.65. I thought maybe something came loose during shipment. The replacement did exactly the same thing. What I’ve found is, you need to put the specimen over the sensor hole with tweezers. Doing it by hand seems to throw it off.Anyway, once I got the technique down, I was able to get accurate readings. It’s a good value for the money.

I really wanted to love this thing. It seems like a well made product, and I have some other Presidium gear that I love. But this thing is just... not at all accurate. It doesn't do what it says it will do.The readings I got from this were NOWHERE NEAR the correct readings for the materials I tested -- and I tested a LOT of different materials, comparing with my regular liquid-based RI meter. The readings from the PRIM II were unusably inaccurate 9 times out of 10. Once in a while, it would give me a good reading. But very rarely.I spoke with Presidium about the readings, thinking it might just be a bad meter, but their general consensis seems to be that the meter's working as it should -- it just doesn't work well.There's some finicky finagling with gems on this -- especially smaller gems (<1/2 ct). Since the sensor looks at a refractive index in one tiny point, you have to move the gem around a bit and find the highest number it comes up with and go with that. LOTS of things trick the light path, though -- inclusions, different thicknesses on the cut, etc, etc. A liquid RI meter balances those out with the liquid. This optical meter does not. The tiniest feather inclusion throws the whole thing off and you get poor readings. It's just... not an effective meter.I had sapphires showing up as Garnet. Peridot showing up as Topaz. Moissanite showing up as Zircon.It just... wasn't good enough to give me even a ballpark on what I'm looking at, even if I KNOW what I'm looking at. An RI meter is only useful as ONE STEP in the gem identification process, but it's a pretty important step. If your suspected green tourmaline has a good refractive index of tourmaline, you can probably narrow things down. But if it's showing up with the refractive index of peridot because your meter just doesn't give the right values, you're left with trying to use a variety of other tests to determine what's right and what's wrong. Having an inaccurate meter like this makes gem identification MORE of a challenge.I'm disappointed, to say the least. Liquid RI meters only go up to about 1.81 in their ability to check for things. That leaves out a good number of gems. But this? This is junk.Save yourself the money.

Comes with nice case and good instructions with included RI card. Appears light and flimsy when compared with a normal analog RI meter, but is actually sturdy and well made and is a precision tool.I actually expected the readings to be shaky and usable only for comparison to a "real" RI meter, and was pleasantly surprised that the readings were stable and precise even on small set stones.The meter has a bit of a learning curve to get quick and reproducible results, and requires a steady base and fairly precise positioning of the stone for best results - it is not a hand held device. However, once you get the hang of it, the meter is a pleasure to use and well worth the price.Anyone who purchases large lots or packets of mixed stones should consider this meter a must have for their bench. It is a quick, easy, and precise for testing the RI of most stones. I have not checked out the included software yet, but I expect that it too will be useful in a number of ways. The box also includes a USB cord for use with the meter.