12 years ago, I bought beads like yours from a Canadian selling in the Chiang Mai night market.
I have never known anything about them. Some collectors suggested they may be petrified ivory.
I assumed they were stone of some sort, but looking closely at the cracking, the organic, wavy look at the end of one bead, I think they may be bone or ivory. So, they may be North Thai rather than North Chinese . . . . the mystery grows!
More looking and clicking - they LOOK like ivory but SOUND like stone. Maybe a dumb question, but could they have been made of already petrified ivory, or could they have petrified since they were made? I have no idea whether this process occurs during the 5,000? or less years since they were shaped as beads. The Wikipedia article doesn't give time frames.
They look filled with clay. Is it soft clay, or hard?
