J.J. is the registered trademark of Jonette Jewelry Co. located in East Providence, RI. The company was founded in 1935 as Providence Jewelry Company by Abraham Lisker and later changed names to Lisker and Lisker Inc. During WWII the firm discontinued production due to the metal shortages that were brought on by the war and government restrictions. The company changed its name to "Lisker & Lisker" when Abraham's brother Nathan joined him in the business. Production ceased temporarily during World War II. After the war, the company reemerged as "Jonette Jewelry" in honor of the Abraham and Nathan's parents -- "John" and "Etta." Since the 1970's, Gordon Lisker has been manufacturing jewelry though some of the work is farmed out to other companies. In 1970, the company began marking its jewelry with the distinctive "JJ" trademark on all pieces. In 1986 they registered the popular "Artifacts" mark. Additionally, the company marketed a pewter line of animals of the American west under the "Santa Fe" mark. Due to international competition, they announced business closure in 2006. Of course, that made their fun novelty jewelry even more collectible. 

Here you can see one of my favorite J.J. pins: https://talkingfashion.myshopify.com/admin/products/9231833924