Heat Sensitive, Color Changing Thermographic/Thermotropic Math lover Pi cup

This cup is for your math lover that memorized the number Pi to the 104th digit :). My son used it a couple of times, it served as a great incentive for him to memorize number Pi. Made of quality ceramics, produced with safe, high quality and environmentally friendly materials. It is in great condition, no chips or cracks 10 oz. capacity. When it is empty, or has cold beverages in it, the cup appears to be black with just 3.14 numbers in green, with the rest of the numbers in black relief. When you pour the hot cocoa in it it brightens up to all numbers to green row, after row, after row.