DBJ is the maker's mark. They are a Jewelry maker based in N.Y. If the ring is made of precious metal it's stamped to identify material and purity. Gold is stamped 24kt, 18kt, 14kt, 10 kt. SIlver S925, S950, S999 or just the number without the prefix. Platinum is marked PT, PLAT or PT925, PT950. The number represents the purity, the number closet to 1 is more pure. Often precious metals are mixed with alloy or copper to add strength.