21 Genuine Diamonds Set in a Sterling Double Heart Pendant.

What I know for sure - 21 genuine diamonds ( I tested them), both round and square, set in a sterling double heart pendant on an 18" delicate sterling box chain. Chain is marked 925, pendant is marked 925 and SUN. What the internet tells me..... Vintage, 21 diamonds, totaling .31 carat weight, set on sterling with a gold overlay on the inner heart. If it's vintage, it's in exquisite condition! Beautiful, lots of sparkle! No tarnishing or patina at all. a little dust in between the diamonds but you need a loupe to see it. I am so in love with this one!