This iconic 1970s pattern go, the "Butterfly Gold" pattern which made its debut in 1972 was designed by Gregory Mirow. The elements of the design are highly stylized: flower, butterflies, sheaf of wheat.

This particular style of cup is made of a product called Vitrelle which is "a tempered glass product consisting of two types of glass laminated into three layers." (wikepedia).

These "hook-handle" cups were made between 1972 until 1982 and as you can see stack easily, one of their selling points. They were designed by Charles B. Ketcham.

Excellent condition. It's time to plan a coffee klatch!