Rechargeable Diamond Tester Pen with UV Light Professional Electronic Jewelry Gem Selector for Novice and Expert [Intuitive & Safe Operation]Featuring an LCD display and LED indicator, our diamond tester delivers precise, easy-to-read results quickly and safely-without damaging genuine diamonds. Ideal for professionals, collectors, and jewelry business owners. [Easy One-Button Testing]Simply turn on the pen, gently touch the gemstone tip, and wait for the audible alert. Real diamonds trigger a reading above 9 with both light and sound signals; no reaction indicates a fake stone like cubic zirconia. [Adjustable Setting for Stone Size]Easily adapt to different gem sizes using the carat adjustment button: activate 1 light for diamonds over 1.0 carats, 2 lights for 0.5 carats, and 3-4 lights for small or finely-cut stones. [Reliable Thermal Conductivity Detection]The tester uses advanced thermal conductivity sensing to distinguish diamonds from imitations. Note: metals may trigger high-frequency sound due to similar conductivity-always follow correct testing procedures and avoid use on metal, skin, or liquids. [Convenient & User-Friendly]Designed for effortless use with clear visual and audio cues. For best accuracy, always touch the rear panel during testing and ensure proper tip contact-flashing or shutdown may indicate incorrect operation. Features: Specification: Model:KD-MD2 Working voltage:3.3-4.2V Working temperature:10-40℃ Product size:158*45*21mm Adapter (not included in this instrument) Adapter voltage:120-240V Data cable plug:type-c Adapter power:1A/2A Adapter output voltage:5V Internal lithium battery parameters Model:14500 Voltage:3.7V Capacity:500mAh Color: Black Material: plastic Package Contents: 1 x Diamond Tester Pen 1x Charging line 1metre 1 x Testing Platform 1 x User Manual Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.