We are unable to review Diminished Value claims for leased vehicles, because the company holding the lease is considered the owner and would file the diminished value claim.
The issue is a legal one; that is, for whose benefit is the collision/damage insurance obtained. Aside from the legal mandate to be insured for liability, lessees have to maintain certain types of property/collision damage insurance to make sure the vehicle is repaired and/or paid for if a total loss. The benefit inures to the leasing company ( aka bank), not the consumer as he/she has no ownership rights in the vehicle.
If your lease was over and you purchased the car from the Leasing Company then, only damage occurred after the purchase of the leased vehicle would give you the rights to Diminished Value.