Vintage Laurel Birch coffee mug

Beautiful 1large mug, probably 12 oz, is in excellent condition! This was a gift from a friend in 1990. Only used for decoration, never put in dishwasher. There are 2 barely discernible spots that I have not tried to remove. See final photo. There is also a discoloration at bottom of cup that may be part of the natural ceramic; see 2nd to last photo.