No the spell Silent Image can never turn any object invisible.

Pathfinder 2E has the spell Invisible Item, that can turn an object invisible. I'm not sure if Pathfinder 1E has the spell, but it's in D&D 3.5E.

You can't cast Silent Image "on" anything.

You can make an illusion of a cloud of smoke, or mist or fog between a person and an object. This would 'hide' the object. But you can only effect a small area with Silent Image, they can still fell around for the item, and would get that 'interact save'.

You could make, say a rock, on top of a fallen item. But, they are likely to notice a 'rock' that just popped in. You can make the illusion of 'the ground' right about the object, though this would be just as noticeable as the rock.

And the wide area 'ground' illusion does not work well, as soon as someone steps thorough the edge of the ground illusion they will get that save.

You sure CAN:

*Make an exact illusion copy of the object, so they won't know what one to pick up. You can get them to waste a round two.

*Make an illusion of a Dome of Force, covered in crackling lighting over the object. They will likely waste a round or two trying to 'get around the dome'. Maybe even waste a dispel.

*Make an illusion of a spiked steel strong box over the object, so it 'looks' like it's 'inside'.

*Make the area around the fallen object look like acid, lava, spikes, or something similar.

*Make an illusion of a trap. Like a loaded crossbow on a stand with a taunt rope going over to the object.

*Make a guardian monster illusion. A small one works best...a snake or spider is perfect

*Make an illusion of a spell effect...or random 'magic' that could be a spell effect. A tiny lighting filled storm cloud, a floating dagger, or a floating skull are good examples. One could easily imagine a custom spell of Stormy's Storm Cloud that can guard a five foot square and shock anyone that approaches. The same with Delve's Deadly Dagger or Von Kath's Floating Skull. The Silent Image can't DO anything....but it LOOKS like it can.

Massive bonus points if your say a drow wizard and you use Silent Image to make an illusion of a large spider....making it "look" like you might have summoned a large spider. Or a field of puffy mushrooms all around the object.

Silent Image does not "do" anything. But it can sure make a foe waste a round attacking an illusion of a spider. And a foe might waste sever rounds trying to figure out some way past the tiny lighting cloud.

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