This gemstone testing equipment is not only a diamond tester, but also a multi gemstone tester. It can detect if a gemstone is real or fake, including: diamond, sapphire, ruby, crystal, agate, jadeite, and other precious stone of various sizes. If the number of lights equals or exceeds 9, and it beeps, it means the diamond is true. * If the lights is about 9 and it beeps, it means the sapphire is true. * If the number is 6.5-7, it means the agate is true. * If the number is 7-8 , it means the crystal is true. * If the number is 6-7, it means the jade is true. Before Test: 1. Put the battery in the tester. 2. Take off the probe cap. 3. Turn on the switch. 4. Make sure only one light light up on the scale. 5. Make sure the " ready lamp" light on. 6. (If test diamond, you then need to turn on the lights number corresponding to the indoor temperature and diamond weight.). 7. (If test other gems, you'd better calibrate the probe, method: by placing the probe vertically on a glass, then adjusting the light to 5, then test the gems.) NOTICE: No matter what gemstone you are testing, the probe needle and the tested object must be at a 90 angle. * When testing diamond, your right index finger must keep touching the metal panel on the back of the tester, while you do not touch the panel if you test other gemstones. * Do Not test any metal. * Do Not wear glove. Product size: 16 * 4 * 2.2 cm. weight: 100g. Power needed: 1x 9V battery (not included). If you have any problem about the testing, please contact us, we would love to help.