Small diamond tattoo on the back of a hand

You will not believe what came up the bin chute on the ninth floor on Tuesday. Sandeep from number 22 heard something knock against the metal flap while he was shouting for the lift, so he fished about with a coat hanger and out came a little clear stone the size of a fingernail paring, sitting in a nest of cold chip paper and a crisp packet. Nobody on this estate owns anything that clever, so we all knew at once it had belonged to someone who was leaving in a hurry.

The caretaker wanted it for the lost property box, which is a biscuit tin behind his desk with two single gloves and a Nokia in it. I told him he could have it when the owner came asking, and not a minute before. He gave me a look like I was ninety, which I suppose I am, nearly. Then Mrs Okafor's boy came up to show me his drawing of a castle, and I noticed he'd put a little gem on the drawbridge, just the same shape, all straight lines and tiny tricks of light. He said he saw it on the pavement outside the Co-op. I asked how he knew it was a diamond and he said his nan wears one, which is more than I can say for anyone in this block.

So I've taken it up to the windowsill in my flat. In the mornings the sun comes straight through it and throws a wobbly little bit of the car park onto the ceiling. I sit with my tea and watch it move across the paint. When you come home at Easter, have a look at it and tell me who you think lost it. I'm not giving it to the council, and I'm not giving it to the caretaker either, so you'll have to help me decide.