Hi there! my name is yonatan and Im new here. i started playing go when i was about 12 (24 now) but left it for quite sometime, and now im trying to come back into it. consider myself a beginner, even though im femiliar with the game for quite some time. never had anyone to play that was actually any challenge where i live, either then pros. started playing on Pandanet a few weeks ago, and its quite a bit of fun.

anyhow, i took out my old go board/table (home made, my mother is an amateur carpenter) and my stones. the stones were a gift from my mom and dad when i left home, and i haven't played with them in a while. the black ones have this sort of chemical smell to them, and i thought about washing them. i have no idea what are they made of though, and how should i wash them. they feel like glass, though they are matte, and the black ones have a green translucency when put against a strong light source, so i thought they might be yunzi stones. they are lense shaped, unlike most yunzi as much as i know. anyone have any idea what they might be and how should i clean them?

Hello!

I'm not an expert, but the dark green hue does indicate you probably have yunzi stones. They are made in both single-convex and double-convex styles.

From Yellow Mountain Imports on how to care for yunzi stones:

I've also read that you should be careful to choose an oil that's suitable for handling by people - some machine oils have warnings on them! Others recommend using mineral oil, but I can't speak to that since I don't own yunzi stones.

as much as i understand, you should not use oils on glass stones. yunzi stones are porous or something, so they absorb the oils, but glass stones would just get sticky and gross.
i really looking for a definitive way to test weather my stones are glass or yunzi. thinking about taking out one stone and dropping just a single drop of lavender oil on it, to see if it absorbs it.

you can post a picture / some pictures here. perhaps people can help you determine the material, though it definitely sounds like yunzi.
what do you mean, 'feel like glass'? i think yunzi does not feel like glass.
also: are you sure both colors are the same material?
the white (yunzi?) should also show some green translucent effect. both black and white yunzi can be oiled.

If the black stones are translucent and green, it's almost certainly Yunzi. They do make double-convex (lens-shaped) yunzi, too. Go ahead and oil them. On the outside chance they are glass, you an always wash the oil off again.

If you have a brass instrument player in the house, I found trumpet valve oil to be good on stones. Remember, you only need a tiny bit.

yunzi IS glass (ceramic actually, but that's still a type of glass)

hi, sorry it took me so much time, i was really busy at work...
well, i tried oiling one stone and the oil seemed to be gone after a few days. not sure if it means the stones absorbed it though... is it suppose to do that? absorb all the oil?
posted some pics for reference. the white is purely white, as you can see. the black is green when put against the light. also posted pics of the one chipped stone that i have, because it shows the green translucency better.

Those are definitely yunzi stones. If the stone feels and looks dry after the oiling but has a better sheen, it's just right. You don't want them to feel oily or leave oil on things.

Wow, those pictures are huge.
You know you can resize them?

Definitely yunzi (the black ones at least).
If they came in a set, then the white stones will also be yunzi. Difficult to note from your pictures.

I have such a set of double convex yunzi. They are my favorite stones. Thank you mum and dad for this beautiful gift and make sure you play them as often as you can.

There's even a Youtube clip on how to take care of yunzi stones.
See http://www.youtube.com/watch?v=zJFdQ7jaDs0.
Make sure to use suitable oil (fine sewing machine oil or something, no vegetable oil).
Normally one treatment suffices for ages.