The designer and manufacturer of these fine, silver cufflinks is Finnish silversmith Martti Viikinniemi. He worked in Heinola from 1946 to 1974. The jewelry designed and manufactured by Viikinniemi seems to have been mainly silver, and in that case there should always be a stamp series that shows the exact year of manufacture. These have the mark N7 meaning the year of manufacture is 1966. MV is the initials. Finnish and Turku stamps. 813H is the silver mark. Period of activity: Viikinniemi was most active between 1946 and 1968. Location: His company, Viikinniemi Martti & Co Ky, was located in Heinola. Stamps: The MV stamp was often used on his items. Design and production Style: Viikinniemi's jewelry represents typical Finnish modernism of the 1960s and 1970s, which emphasized simple shapes and often large natural stones. Materials: He used silver (often 813 or 830 fineness) as his main material and combined it with various stones, such as amethyst, rock crystal, specrolite and tiger's eye.