Tiny gray dwarf hamster with white belly

I lost my tiny gray dwarf hamster, Nibbles, yesterday around 4pm near the Mall del Norte on Del Mar Boulevard in Laredo. He's about the size of a toonie, with soft gray fur, a white belly, bright black eyes, and a tiny pink nose. There’s a small white heart-shaped patch on his chest, and he wears a blue harness with a little bell. I last saw him by the pet store entrance near the food court. This little guy was a Christmas gift from my grandma, so I’m really worried and just want him back safe—if you spot him, please message me and we can arrange a pickup near Mall del Norte.