Dynamic Gemological Refractometer w/ Built-in LED Light + External Light Source ***** *****           This Gemological Refractometer has New Special Design Features. It offers Built in LED light & External Light source (flashlight). A small torch or flashlight (FREE & included in the set), a desktop LED light (optional & not included in the set) and other light source can be use as its source of light when the built-in light source won't work. The built-in LED light source can at least offer 10000hours working. It has a light entrance at the back and a built-in filter for the external source of light. This instrument is considered to be the most important of all gem testing instruments. It measures the angle at which light traveling through the stone is bent or refracted, called the Refractive Index (RI). Use this to measure Refractive index of Gemstone or Ore, index of double refraction and identify/authenticate polished precious and semiprecious gemstones as well as observing the optical properties and the structure of gemstones, transparency or opacity and its beauty, durability and scarcity. Due to chemical composition and crystallization structure, each gem has a typical refractive index. You can also use this tool to measure R.I. for many minerals in crystal form as long as the crystals have a flat and polished face. Through these parameters, you can determine whether the gem is a Single Refraction (Isotropic) or Double Refraction (Anisotropic or Birefringence) and uniaxial or biaxial photopositive or photonegative.   Special Features NEW DESIGN 2 in 1 Light Source: Built-in LED Light + External Light Source (flashlight) Built-in LED illumination Built-in Light Source Filter for outside light source FREE Index Fluid and small flashlight/torch Convenient & easy to carry Durable and very reliable Characterized by small volume and less weight A popular instrument used on jewelry market Approved by strict quality and safety standards   Specifications Filter: Polarizing filter Measuring Range : 1.30 - 1.81 RI Minimum Graduation : 0.01 RI Accuracy : ±0.02 RI Illumination : Internal LED Light Source with momentary/power switch Power: 1.5V Button Batteries (3pcs) Dimension : 30 x 70 x 130mm Weight : 400g Ranges of Application: Laboratory, Gemology   Set Included: 1 x Vial of 1.800 Refractive Index Oil (FREE) 1 x Flashligt/Torch (FREE) 1 x Polarizing Filter 3 x 1.5V Button Batteries (FREE) 1 x Cleaning cloth (FREE) 1 x Reference Block (FREE) Sturday and Hard carrying case Instruction Manual Optional: Desktop LED Light Just add US$12.00 or AU$14.00 or GBP8.00 to your order to have the optional Desktop LED Light in Extra     Copyright © 2008. All rights reserved. Discount Instrument *