By definition, true porcelain is impermeable and translucent. If you shine a light behind true porcelain that is not painted or glazed in an opaque color, you should be able to see the light glow through it. Another method is checking to see whether unglazed areas of the porcelain object become permanently stained (by tea or dirt, etc.) or whether they can be easily cleaned. True porcelain that is high fired will be impermeable and will not stain under the surface, making it easy to clean.
Every piece of ceramics found in this section of the site is made from one of the finest and purest porcelain in the world.