Is this toning or not? I think it looks pretty cool. Unlike the others I have, this one has something like zebra stripes on the front and back.
I'd say that's what in U.S. copper cents we refer to as a 'woody' for it's similarity to wood-grain, which is due to the composition of the metal not being insufficiently blended when making the sheets/strips of metal for the coins. FWIW, I've seen this composition imbalance commonly occur with modern 100円 coins. U.S. nickels (.05¢) also have this 'wood grain' effect. Your coin has quite dynamic patterning and, for me, that benefits it's eye appeal. Thanks for sharing.
I think you can get that chocolate-y look by applying sealant waxes or various oils to copper coins*... or by just buy chocolate gold coins themselves *not that I would recommend doing that.
You mean the stripes or just the overall brown color? I bought a big sack of Taisho to Pre-WWII coins from this guy in Japan. Almost all of them are well circulated, and therefore have this brown color, I did find one that looks like this though. The sen on the left is the one that looks like it is halfway between circulated and uncirculated. You can still see that shiny copper, like a new penny. The sen on the right is like fully circulated; 100% chocolatey I love Japanese 1 Sen coins. Many issues, a few varieties, and they are relatively cheap since the rarest of them is still about 3 million issued. Well, I think the 1873 sen has only like 1.3 million.
The overall brown color is what I was joking about bringing out on copper coins with sealant waxes. The 'stripes' or wood grain is the metal itself and fixed.
