Ruska (autumn colours, brown) is made with black powder (iron) which was blown under the brown ceramic glaze, so that each item is unique with a changing amount of black spots on brown.
A mug is a larger type of cup typically used for drinking hot beverages, such as coffee, hot chocolate, soup, or tea. A mug is a less formal type of drinkware, and is not usually used in a formal table setting.
These mugs are otherwise in good condition, but they have some scratches inside from being stirred with a spoon. They are otherwise not a bother, but when light hits them right they can be clearly seen. See the additional picture for an example with powerful light.