What is an electronic diamond tester?

In today’s diamond market, synthetic diamonds are often hard to distinguish from real stones. Synthetic materials, like cubic zirconia and moissanite, both create an imitation stone that looks much like a real diamond to the naked or untrained eye. Diamond buyers and sellers have come to depend on electronic diamond testers to ensure the diamonds they purchase are genuine. Diamond testers are really useful in checking for diamond imitations. Synthetic stones, such as strontium titanite, or zircon, tend to have high refractive indices. The high refractive indices make the imitations look more like a real diamond than those with low refractive indices, such as glass. The higher the refractive index, the harder it is to differentiate between synthetic and real diamonds. People with no knowledge of gemology often find it very difficult to identify these imitations, making an electronic diamond tester a useful tool. 

There are many diamond testers available on the market. Below is a list of our favorite testers: 

The Presidium DiamondMate-C offers fast, easy and reliable testing. Visual lights and audible beeps make reading results seamless and easy to understand. The thermal conductivity method allows for reliable, precise results. The Presidium DiamondMate-C requires very little battery consumption, allowing for prolonged use without worrying about battery life. As an added feature, this diamond tester also has a built-in metal detector that beeps when it comes in contact with metal.  
GemOro Superior Instruments Testerossa Diamond Tester
The GemOro Superior Instruments Testerossa Tester is the next generation of diamond testers. Featuring a fast 10 second warm-up, glowing light bar/probe tip for quick stone identification. Results can be delivered through programmable languages or various ringtones. This innovative tester has the sleekest ergonomic shape available, allowing it to comfortably rest in your hand. The LED stone illumination and UV fluorescence detection allows for fast, reliable and easy use. Precision retractable probe-tip with enhanced durability, and indestructible polycarbonate housing with molded rubber base make this diamond tester impact resistant. The tester is powered by a micro-USB or with the included rechargeable NiMH batteries.  

How to use a Diamond Tester

Most testers are easy to use. They work by pressing a metal point against a facet of a stone. The metal point heats up. The tester then detects the rate at which heat transfers through the stone. The way heat transfers through a synthetic material, such as cubic zirconia, greatly differs from how it transfers through a real diamond.  The diamond tester will then give a signal that indicates if the stone is genuine or not. Using a diamond tester is fairly simple, but below you can find a list of tips that will be helpful if you’re using a tester for the first time: 

  1. Most important, the stone must be cool before using the diamond tester. A person’s body temperature can warm a diamond sufficiently just by wearing it. This will affect the reliability of the test. If a genuine diamond is too warm when tested, it may result in an inaccurate reading. If the stone was being worn, remove the stone from the person’s body and allow it time to cool. You can also cool down the diamond by spraying it with an upside-down can of compressed air, or placing it under cold water and wiping it dry prior to testing.

Gemlogis Lapis One | new product sold by Stuller  

Gemlogis Lapis One Electronic Diamond Tester
  1. An adjacent diamond cannot be tested right away. You cannot get a reliable reading if you consecutively test stones that are adjacent to one another, because the electrical charge transfers heat through the entire stone, as well as any adjacent stones. Since the adjacent stones are now warm, the tester may give a false reading.  After testing the first stone, allow time for the stones to cool, and then repeat the process for all adjacent stones.
  2. Stones cannot be retested immediately. The stone will still be warm from the initial testing and needs time to cool down. 
  3. Be sure the pointer is not touching metal. Electronic diamond testers will not work properly if the point is touching any metal, such as a bezel edge or a prong. Be sure the point is not in contact with metal. Some models have a metal detector to warn you of nearby metal.
  4. Keep the battery well charged. If the battery is not well charged, you might not get an accurate reading. Most models now have an indicator that tells you if the battery is insufficiently charged, but remember to check before you begin testing.