The Pioneer Woman Set of 2 Jadeite Glass Coffee/Tea Mugs

So beautiful! Sleek, elegant, jadeite glass. Stunning scrolled handle and scalloped rim. Each cup stands 4.5" tall, mouth is 3.75" diam. No chips or cracks. One of the cups has a dark spot at the bottom that I have tried to get out but cannot. I'm not sure what is. This could have been done during production. Dishwasher safe. Not for microwave or oven use.