it's not as versatile as an optical refractometer, you only get one reading for each stone (technical: you can't measure the birefringence). This means that if you want to distinguish diamond simulants you need to compare actual stones (get a sample set of stones: YAG, GGG, synthetic sapphire, synthetic spinel, zircon, strontium titanate and cubic zirconia) it is an extraordinarily sensitive thermal conductivity meter, and is therefore very sensitive to heat. If you are not using it at room temperature you must calibrate it (not difficult but it does take several seconds); it really will not work at all if it's very cold (e.g. outside in the winter in Northern Europe) You can see from the picture which stones it will test, also note how the readings overlap. It is for this reason that I say the tester is best for showing what a stone is NOT rather than what it is, e.g. a customer is offering you a sapphire, you can see that it might be glass, it might be garnet...but it can't possibly be sapphire. Despite its limitations, it is still useful for pulling out gemstones worthy of further investigation, e.g. you may be interested in stones that might be ruby/sapphire and not at all interested in anything that is probably glass. It is also particularly easy and fast to use and can be used on any stone no matter how it might be mounted.

For accurate and reliable gemstone testing, the Presidium testers are an essential tool for the workshop. Presidium offer a range of electronic and dial gauges, as well as digital testers, that use advanced technology to help identify a range of stones. Ideal for use with both loose and mounted stones, Presidium testers can help you distinguish diamonds from other stones and convert gemstone dimensions to estimated carat weights. Browse the range and find the right tool for your workshop today Yes, that is what is so good about this one, it can test any mounted stones (other models either don't test mounted stones at all, or are limited to small rings). you must read this before buying an electronic gem tester (whether you buy it from us or anyone else!) To test if a diamond is real, you will need to place the tip of the tester on the stone’s surface and detect the rate at which heat or electricity moves through the gem. If the diamond is genuine, the device will indicate that on the display and give a sound signal. What Type of Diamond Tester Is Better?You notice that there isn't a reading not diamond ("simulant"); if you are not a diamond dealer or experienced jeweller you must be certain you are testing a stone that will register 'diamond' on most diamond testers; testing non-diamonds on a Synthetic Diamond Tester can give incorrect readings. Technical The Presidium ARI is an essential tool for the experienced jeweller and professional diamond dealer, it is for testing known diamonds. Gem testers merely suggest possibilities and you must use a combination of experience and other tests to come to a conclusion. If you see a gem tester (any gem tester!) elsewhere with a "100% guarantee" of accuracy, let us know where you have seen it.

My advice: if you want to test diamonds/Moissanite in a busy shop or at markets and fairs, get a Diamond/Moissanite ('multi') tester, they are very easy to use, especially if you are working under pressure. If you are working in an office where you can sit comfortably at a desk and work slowly and carefully, then get a reflectivity/Refractive Index gem tester as listed below. If you manage a group of stores (or an auction house) that does both - then get both. THERE ARE TWO TYPES OF ELECTRONIC GEM TESTER If your tester works consistently (it gives the same reading on the same stone every time) and correctly (it accurately identifies stones) then you really don't need to know the principle on which it works. However, if you are having problems (and you have read the instructions and are certain you are using it correctly) - then a knowledge of the principle will help. you are in dispute regarding a stone that you know for certain is not diamond (because you have a diamond tester), it looks like diamond but it is an imitation - what is it? The Presidium ARI will distinguish most synthetic diamond from natural diamonds. It will also detect Moissanite. The Presidium ARI is not a diamond tester for distinguishing diamond from non-diamond, if you need a 'diamond tester, you can find the product here, or see our general guide to buying diamond testers.

It is time to know the difference between a genuine earth-mined diamond and a lab-grown one. Our BELIZE Natural Diamond Tester delivers the most accurate and reliable results when identifying a natural stone, moissanite or simulant. The Gold & Silver Buyer’s Handbook is the ‘bible’ of how to test, buy and sell precious metals - from collecting and part-time dealing, to working with scrap and jewellery in large companies. Diamonds have very high thermal conductivity, they 'draw' heat, they are used extensively in the electronics industry to 'remove' (conduct) heat (they use diamond-coated components not gemstones), it is the high rate at which diamonds conduct heat that makes them react on a diamond tester and which makes them feel 'cold-to-the-touch'. If you’re selecting a lab-created or natural diamond, make sure it’s certified by renowned institutes such as IGI and GIA. Certified diamonds are a good way to ensure authenticity, and they also come with details about the quality.