WebThe Chelsea filter is a dichromatic filter which transmits two wave lengths only – in the red region at 690nm and the other in the yellow region at 570nm. The presence of the elements chromium or cobalt in a gemstone makes it appear red when viewed through this filter. ... Presence of iron tends to retard or dampen the red colour in emeralds ... http://www.gemstonepress.com/instruments/chelsfilt.htm

Color filters distinguish gems - A. KRÜSS Gemmologie Shop

WebChelsea Filter. One of the most popular filters is the Chelsea filter. Originally used on emeralds, it can help you distinguish an emerald lookalike. The Chelsea filter allows … Hold the filter an inch or two from the eye. Light the stone with a strong incandescent light bulb or torch, not LED. The stone may appear to change colour. The filter must be held near to the eye but there is no need to hold the filter close to the stone, even items in showcases can be examined providing … See more In gemmology, a Chelsea filter is a dichromatic optical filter used for identifying coloured stones. See more • Infrared filter • Optical filter See more The "chelsea" filter was originally devised by Anderson and Payne in 1934 of the Gem testing Laboratory of the London Chamber of Commerce & Industry. The filter was devised with the collaboration of gemmology students of the Chelsea College of Science and Technology See more • Chelsea Filter - Gemstone Buzz uses, procedure & precautions. • Instructions for Chelsea Filter • MineralLab & other type of filters See more tag agency quakertown

Foldable Ruby Filter Identification Tool for Emerald and Gemstones

WebThe Gem-A Chelsea Colour Filter allows transmission of both deep red and yellow-green wavelengths of light. Useful for separating stones of a similar colour. Please note this … WebThe GemVue TM Chelsea filter is constructed of metal for durability and has a gloss white finish. It features an 18mm filter lens and notched frame for easy operation. The design is compact and fits easily in a pocket. Mexico: a $10.00 surcharge per item will be added to the U.S. shipping fees listed above. WebThe filter was developed with the collaboration of gemology students at the Chelsea College of Science and Technology, hence the name. A Chelsea Filter is a dichromatic optical filter, meaning that it allows transmission … tag agency ponca city