Hi everyone,

I was playing with my yunzi today, and one of the black ones felt lighter and thinner than the others, which I thought was very strange. At first I thought I might have mixed it up with one of the Korean black glass stones, so I held it up to the light to see if it had the green ring, but instead of a green ring it had a pink ring. Has anyone ever heard of something like this before?

I just thought this was very weird and thought maybe someone on here would know about it.

Weird! All of my Yunzi stones are the standard green. I'm very curious about the cause.

By any chance have they been exposed to the sun? Some metals will oxidize faster in glass when exposed to sunlight, causing a purple or pink color. This can also happen just with age.

Well these stones are kind of old. I got them five years ago. But I don't think any of my stones have been out in the sun for very long if at all.

I am not even sure what causes the green rings in the first place.

Off topic: When I was a kid, living in Albuquerque, New Mexico, we found some old Coke and medicine bottles while out on our bikes in the desert. ON the advice of Pete's older sister, we lined a wooden box with aluminum foil, put it on MacAnally's garage roof, oriented it to the south, put the bottles in it and tried to forgot about the contraption and the experiment for one and a half summers. When we were up there retrieving a Frisbee, we peeked inside and were astounded to find the cheap glasses' colorants had speed-oxidized to several shades of green, blue, aqua and pink.

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David Bogie, Boise ID
I play go, I ride a recumbent, of course I use Macintosh.

Hello MrNoob it's been a while, I didn't expect to find you on here.

I may have figured a small bit out about your current anomaly. Though no one outside of Yunnan truly know what exactly is in Yunzi stones, it is widely speculated that the material found in the stones is mined within the mountains of the providence. Luckily we happen to know that the Yunnan area is home to the mineral Jadeite which I'm sure you could guess is one of the two key components to the rock known as jade (The other component being Nephrite which for this purpose is not to important). Jadeite can range in color from green, white, blue, lavender, and also pink. More likely than not the Jadeite used for Yunzi stones is a particular sub-type known as Chloromelanite which presents it self as a very dark green, so dark it often appears black. Which is likely what causes your green hue when you hold a yunzi up to the light. The color of Jadeite is heavily influenced based on trace elements of iron and chromium.

How your one stone turned pink, I can't say for sure. But perhaps it has been pink all along? It may be possible that it was an un-pure stone which slipped through quality control? Or maybe for whatever reason that stone has reacted with your everyday use of it in a way the others haven't.

Hopefully this is of some help, or interest.
{A quick edit, this is all speculation. I am not claiming of having any advanced knowledge of the Yunzi process or chemical makeup. I am simply proposing a theory which could lead to an explanation for the above problem.}

Ilyo.

I have some stones that look like Yunzi, but the halo is brown. Don't remember where I got them. Any ideas?

Glass? I've got some cheap glass stones that have a brown glow when silhouetted.