Chelsea Filter Magnifier Style_Accessory and through the viewfinder you

and through the viewfinder you see a scale

Takes one 9v PP3 battery (supplied)

Battery-powered plus a USB cable is included for other power options

For measuring specific gravity

The battery icon on the display means low battery

Chelsea Filter Magnifier Style_Accessory and through the viewfinder youSummary The original Chelsea Filter, as developed at the Chelsea College of Science and Technology in 1934. Do not confuse this with the many copies. Detail Many stones appear to change colour when viewed through the filter. Originally designed for detecting synthetic emeralds, nowadays the Chelsea filter is an invaluable aid to identifying many other gemstones. It can give an indication that you have an emeralds and aquamarines, though not a