Opal body tone and brightness scale dark-opal Each opal is approx 7x5mm

Each opal is approx 7x5mm with a low dome

What a stunner

Stunning Chinese writing in this gem black opal

A top high gem black opal with a nice high dome and very bright colors

Opal body tone and brightness scale dark-opal Each opal is approx 7x5mmSick 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 created 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 worldwide. The brightness is