1. Fast and : Professional Diamond Selector II will indicate genuine diamond or fake. It is designed for quick, precise, and diamond testing. LCD display LED indicator. Uses large / small switches for testing diamonds, Emits audible sounds to easily differentiate the readings. 2. Bare Hands Operation: All the tests must be done by your bare hands. If you put on your gloves, the metal alert will not function since a normal moisture level of your hands is necessary for operation. All test must be done by TWO hands, one for hold the diamond and one for the diamond tester. As for the hand which hold diamond tester, you have to touch the electricity conductive panel on the back of the unit. If you test the diamond just by one hand, you will get a wrong result. 3. Beeping Upon Startup: Ensure correct installation and adequate power in the test pen battery. Also, clean the test pen probe as maintaining its cleanliness can enhance testing efficacy. A beeping sound upon powering on signifies the need for initialization settings. Consult the table on the rear of the machine for the specific initialization settings considering the diamond's temperature and size. Adjust the initial number of illuminated lights by rotating the knob (the default setting is to have 4 lights illuminated at room temperature). 4. HighFrequency Sound when Testing Metal: The highfrequency sound during metal testing is due to the test pen's operational principle, which relies on thermal conductivity to distinguish between diamonds and fake gemstones. Since metal possesses thermal conductivity similar to diamonds, it generates a highfrequency sound during testing. 5. Simple to Use: Diamond Tester Pen is simple to operate to get results, professional(s) are not required. Simply turn on our Diamond Tester Pen detector; place the tip of the Diamond Tester on the gem stone (lightly pressed is sufficient) and If the stone is fake, crystal or cubic zirconia, the tester will not beep. 6. Note: The battery temperature is lower than 10 degrees Celsius, which seriously affects the use time. Don't wear gloves,Don't detect metal. Best to measure in no wind conditions,The operating temperature is within the range of 10 35 degrees Celsius, and the humidity is below 80%. When testing diamond, your right index finger must keep touching the metal panel on the back of the tester. Please turn off the power after the test to save power.