No direct boiling water, otherwise use as any normal glass.
The process involves collecting used glass, sorting then melting in mud / stone ovens. They then mix pigments in and manipulate with air and simple tools to create their forms, some of which like the process have not changed for thousands of years.
Youssef has specific glassblowers he works with in Damascus Syria. He imports his pieces to EU only three times a year by sea and has a small atelier in Paris where he constructs his pieces ( light fixtures and other deco objects ).
The glasses range in size and are traditionally used for tea / coffee. Shapes are similar but each piece is unique / one off.