"Mine have what looks like a colouring treatment to bring out the banding but it hasnt taken evenly."

You mean someone had treated them on purpose to make them look more beautiful?And the colour is not what it was originally?I am not so familiar with those kind of stuff and know little about their history.What I want to know most is how long had it been since man began to treat agate on purpose("colouring treatment"for example)It is said that this kind of technique had not come into being until Qing Dynasty in China

"Would you say that's the case with yours?"

No,of course not.I have only several agate beads coming from Inner Mongolia.You can find them from my post:"Chinese beads of different ages"(I will take some close-look picture next time).Most native people in China believe those kind of beads were probably made during Liao Dynasty(from the drilling and the surface).But there is no records show there is "colouring treatment" at that time...

Christina