Pretty sure it's sterling silver, but I'm not an expert in precious metals, I am sure that it's silver though. Unfortunately the handle is hollow, but I am confident that this isn't a plated knife. It has the old markings on it, and from what I've found in research, it's not likely this was plated, and I'm not seeing any indicators at all to suggest there is plating, quite the opposite actually.

Thank you for the tip with how to clean it up. I'll be sure to make a follow up post about this once I have an appraisal and have it looking nice. Thanks bro.