Fortnum & Mason Glass Mug with Filter Fortnum’s Glass Tea Infuser Mug At Fortnum's, tea is for more than just for sipping, it’s for life. And as it has been since 1707, our belief is simple – whatever the occasion, wherever the location, there is no greater pleasure than taking time for tea. This smart glass travel cup ensures you can enjoy your favourite cup of tea no matter where you are. Care Guide: Not dishwasher safe - hand wash only. Blue edge around top is silicone, a Tiffany blue color.. so pretty!