The Gemological refractometer is considered by many to be the most important of all gem testing instruments. The primary use of the refractometer is to measure the angle at which light traveling through the stone is bent or refracted. This is called Refractive Index (R.I.). As Refractive Index is usually different for different gemstones, this provides an important clue for accurate gemstone identification. Gemological refractometer also can be used to determine whether or not a stone is single or double refracting. For doubly refracting stone, based on the difference between 2 readings you obtain from the refractometer, strength of the gemstone's double refraction (birefringence) may be computed and it offers an important gem identification aid, as it differs from gem to gem. Also refractometer is one of the few instruments capable to give you information for opaque stones as well as transparent stones. Quality of the instrument is important to enable you to perform consistent and reliable test for years to come. Our refractometer has all metal construction with built-in light (no flashlight or any other light source required) and polarizing filter, allowing you to perform all needed tests, it comes with vinyl soft case with belt loop for convenience while traveling and hard case for safe storage. Features: All metal quality construction Built-in LED light source with 3 x 1.5v batteries - included Accuracy: 0.01 Measurement range: 1.30 - 1.81 Polarizing Filter Weight: 0.9 lb Application: Gemology Hard and soft cases are included R.I. liquid is not included, please purchase certified R.I. oil from reputable sources. Please be aware that R.I. liquid is not included. Many in stock! Ships ASAP from USA! Quality all metal construction Measurement range of 1.30 - 1.81 Built-in LED light source with 3 x 1.5v batteries - included Considered by many to be the most important of all gem testing instruments Polarizing Filter, Hard and soft cases are included International Shipping: Shipping will be via US Postal's Air Mail/Global Priority (3-8 business days) is $15.00 ($12.00 to Canada) . There can be Customs delays, and there aren't any Tracking Numbers. WE ARE NOT RESPONSIBLE FOR CUSTOMS DELAYS OR LOST PACKAGES! We get the packages to the shipper, they ship it to you. Don't worry! They do have wonderful service and assist in reducing your import taxes. Buy more items, for a total of 2 portable refractometers, and the shipping charge is still just $15.00 (world)/$12.00 (Canada) via the Air Mail/Global Priority! Of course, you'll have to win this auction to get the first item! Air Mail/Global Priority: World: $15.00 Canada: $12.00 For an additional $15.00 you can upgrade to USPS Express Mail (which takes 3-5 business days) and includes Shipping Insurance to $100.00, Delivery Confirmation and a Tracking Number. National Industrial Supply 30777 Rancho California #891420 Temecula, CA 92591, USA Sales: 951.308.9269 Fax: 310.833.7306 Email: [email protected] We prefer Paypal! Pay me securely with any major credit card through PayPal!