The imprint "75 Years / Omas / Symbol of Distinction" combined with "750" marks special anniversary editions released by OMAS around the year 2000 to celebrate 75 years of Italian pen-making heritage (founded in Bologna in 1925 by Armando Simoni). [1, 2, 3]
The number 750 stamped on the nib or trim is the European millesimal fineness hallmark designating 18-karat (18k) solid gold (75% pure gold