Kim Kardashian's Ring Can Be Tracked

Kim Kardashian's confident she'll get back her multi-million dollar ring because it's very rare with unique identifiers.

Sources close to Kim tell TMZ ... she believes if anyone tries to sell the ring they'll find it. The police report she filed includes the diamond's inscription number and other markers that will raise red flags if it ends up on the market.

The Gemological Institute of America says inscribed diamonds have a microscopic number laser-inscripted on the girdle of the stone. Once a police report is filed, any lost diamonds would be flagged in the system, and if they pop up for a cleaning, grading or possible sale ... police are called.

Even if the inscription is scratched off, rings like Kim's can be identified by special internal characteristics of the diamond ... according to the GIA.

It's not foolproof, of course. Big diamonds can be crushed into several pieces so they're less traceable -- and if crooks avoid legit jewelers ... there's less chance anyone reports a run-in with the stolen rock.

Bottom line: Kim needs the thieves to make a dumb move in order to get back the diamond.