Kutani porcelain is very thin. I placed a picture of the teacup against the light and it’s almost transparent. You can see the painting on the inside, but it’s surprisingly durable. This is a beautiful set .The colors and design are beautiful. However, you can tell that it was not made in a studio. It was probably mass production mid 20th century that’s why you see little sliver of paint here and there in places like inside the cup. This fact does not take away from its beauty. They survived for many years, still collectible, just not high end. After all, isn’t beauty in the eye of the beholder?