This is quite a rare charm, it's a vintage solid 9ct yellow gold Ruler charm, representing the traditional six inch type of yesteryear. 
 
On the front it has inch graduations and on the back is inscribed the words ‘The Golden Rule’. 
 
The Golden Rule is an excellent principle for life, treating others as we would wish to be treated, and this is a golden ruler. Rather a good pun.
 
In excellent condition and fully hallmarked for Birmingham 1967. Comes with a jump ring ready to attach to your bracelet.