This was a gift from Fukushima. I think it's a Japanese horse chestnut. It's round and a cute charm. The nut in image 2 is a little bigger and has a hole for a string. The hole is irregular, which is how it was when purchased. The bottom nut: Diameter: Approximately 2.7cm Thickness: Approximately 2cm Image 8 shows a 100-yen coin for comparison. Image 9 shows the overall size. Please check the size.