I am not sure how this happened as the cup is made for hot beverages. After owning the cup for 1.5 months, I thought there was a stain I cold not remove, turns out the inside has developed a crack. The cup was never dropped and there is no damage to the outside. I am pretty sad as I loved the pattern and the size with the covered steeping top. I will update this review and let you know how customer service responds to this problem.