User blog comment:TravelAddict1967/Cersei's wine glasses at King's Landing/@comment-33163167-20170923004939

Actually, they are made by http://www.sklarnatomi.cz/index.php. That is where merchanventures gets them.

http://www.rozhlas.cz/kraje/cesko/_zprava/pohary-ze-sklarske-huti-ve-vrbne-pod-pradedem-se-dostaly-az-do-hry-o-truny--1637932