Chelsea Filter Magnifier Style_Accessory The battery icon on the

The battery icon on the display means low battery

not only opens small screw-backs (18mm) but also large watches

Takes one 9v PP3 battery (supplied)

For measuring specific gravity

Chelsea Filter Magnifier Style_Accessory The battery icon on theSummary 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