This is Ritzenhoff.
Glass manufacturer “Made in Germany”.

For over 100 years, the heart of Ritzenhoff Cristal GmbH has been beating in the Sauerland region, in the heart of Germany. Surrounded by forests—whose wood was already used in the 18th century by the first glassmakers to melt quartz sand into glass—stands one of Europe’s most modern glass production facilities.

“Made in Germany” is a core principle at Ritzenhoff. The company not only produces 50 million drinking glasses for the international beverage industry, but also designs, refines, and ships them worldwide from its own logistics center.