Blue polki diamond pendant and chain necklace in sterling silver

This pendant and chain necklace are in excellent pre owned condition showing little to no signs of wear.  Blue colored natural mined Polki diamond set in a sterling silver pendant. Likely plated with rhodium or platinum to slow down tarnishing. Chain measures 20 inches in length and is also sterling silver with a lobster claw clasp. 925 Djoy . Diamond has likely been heat treated for color