If you have the sound jin but not the character, here are the 4 characters read this way: 金 (jīn, gold, metal, money), 紧 (jǐn, tight, taut, tense, urgent), 进 (jìn, to enter, to advance, to take in), 近 (jìn, near; close; recent). They split across 3 tones, so the tone is what separates them.