Item Description: RGM-100 Portable Gemological Refractometer with a flashlight Comes with instructions! Written by our staff, not converted from another language! Comes with a Gemstone Refractive Index Chart! Comes in a black zipper case! Product Specs: Measuring Range :1.30 - 1.81 RI Minimum Graduation : (RI) 0.01 RI Dimension : 125mm x 70mm x 40mm Scale Division : 0.01 nD Weight : 0.4 kg Ranges of Application : Laboratory, Gemology Power Source : 3 x AG13 1.5V button batteries One BRAND NEW RGM-100 Portable Gemological Refractometer in a Black Vinyl Zipper Case in a sturdy hardcase. This handy little piece of equipment tests a gemstone's ability to slow down or bend light. The amount of slowing down it does to a beam of light is called the refractive index. THIS UNIT WILL HELP YOU DETERMINE WHICH GEMS ARE REAL AND WHICH ONES ARE FAKES! THIS UNIT HAS IT'S OWN INTERNAL LIGHT SOURCE! NO FLASHLIGHT! How does it work?: The refractometer works by the use of a glass hemicylinder inside that has a flat surface extending into the body of the refractometer. When light is introduced into the back of the unit, it travel through the glass hemicylinder and up to the gemstone, where the stone is in optical contact with the glass by use of a refractive index liquid. This liquid keeps air from between the stone and the glass hemicylinder and allows light to travel at the same speed through the glass, gets refracted by the gemstone, and then back through the glass hemicylinder to the viewing lens. The amount of slowing down or bending of the light that the gemstone does to the light beam, causes a light and dark area joined by a thin green line. This green line is the refractive index reading of the gemstone. Included are: * Black Vinyl Softcase * Polarizing Filter * Monochromatic Light Filter * Flashlight * Users Guide, BEGINNERS HOW-TO Guide EXTRA FLUID: Add a 10 Gram vial (about 2.5ml) of 1.81 RI Fluid for an additional $59.99. S H is FREE when shipped with your Refractometer! We have several sizes to choose from! Several Refractive Index values too! Check out our store at www.nisupply.com! High Quality! A deal is only a good deal if the quality is excellent and the seller is still around after the sale for any questions you may have! For LARGER ORDERS, please check out our Store! --- click the tag! International Clients: We ship packages via US Postal's Global Priority Mail/Air Mail for $15.00 ($12.00 to Canada). It takes about 3-8 business days arrive (please note that there can be Customs delays from time to time). Questions? Larger orders? Please e-mail us! DO YOU NEED MORE EQUIPMENT? CHECK OUT STORE AT WWW.NISUPPLY.COM FOR EVERYTHING THE GEM ENTHUSIAST NEEDS! For inquiries about this product, please contact me at the e-mail address below. National Industrial Supply 30777 Rancho California #891420 Temecula, CA 92589, USA Sales: 951.308.9269 Fax: 310.833.7306 We prefer Paypal! We accept Cardit Cards via phone, fax or e-mail too!!