Value:  Lots.

It's a Stevens Sure Shot, one of the earliest and rarest of the kids' rifles they made.

While you serious shooters can chuckle all you want - the "diamond" is, of course, an all-too-common stock repair - the Stevens "Sure Shot" is indeed very highly desired among those who collect Stevens and boys' rifles, among others.  And while it's especially dangerous to judge from such an abbreviated photo, if the rest of the gun is as good as the plating and barrel bluing suggest AND if the extractor works and has not been repaired/replaced/modified, I'd lowball your little rifle at more or less $1000.

Bill Lawrence

Definitely valuable. Only made for a short time. Not a very tough gun. Standard velocity ammo only. I shoot mine but not much. Action is weak. Looks like a nice one. Hard to find one at all and harder to find one in that good shape. I passed on a rough one many years go that was cheap but rough. Finally found a nice one several years back and it was not cheap. Prices keep going up on the rare ones. The diamond on the stock is not factory but as nice as the gun is I don't think it hurts the price at all. There is currently one on Gunbroker with a $1200 minimum bid. It has been refinished and has initials carved in the stock. Also some history in the description.