Opal Body Tone and Brightness Scale It also has a millimeter

It also has a millimeter measurement down the side to measure your opal when grading them

The brightness is simplified into 5 levels to support the measure of an opals brightness(B)

giving you a reliable grip no matter the season

Opals not included

Instructions for use are on the scale

Opal Body Tone and Brightness Scale It also has a millimeterSick of trying to guess what the body tone and brightness of your opal is? Now you can accurately measure from a calibrated scale. This scale has been designed by Black Opal Direct with a durable plastic material and is compact to ensure you can take it anywhere. It will help you grade your opal with ease only to be used as a guide. The body tone(N) values have been measured by Anthony Smallwood the author of the official grading system used