Lost cat: blue-grey tabby with red collar

I'm heartbroken—my cat Luna disappeared yesterday afternoon around 6pm near the Grainger Market on Grainger Street in Newcastle. She's a blue-grey tabby, about 4 years old, with a bright red collar and a tiny silver bell that chimes when she walks. She has a small white patch on her chest and a notch in her left ear. She’s shy with strangers, so she’ll likely hide if approached, but she might respond to tuna or a familiar voice. This cat means a lot to me and my daughter; we’re really hoping to have her back.