Grandmas Diamond Ring

Hello, My mother passed and left me grandmas dimond ring. Stamped inside with " H then an arrow followed by a 9. I'm just wondering how to find out more about this ring. I think the 'H's for the diamond color and the 9 might be the size, The 'arrow' in the middle a hallmark, but I'm not sure. can you give me any information please. thank you Reggie