Never pay down a deposit in a bank account until you have met the seller, seen signed a purchase agreement.
No serious private advertisers ask for a down payment before you meet.
Receiving an email with an in-scanned ID does not mean that you have identified the sender. You do this on the spot, when you sign a purchase agreement.
I am interested in selling my old coin; here are the details: Coin Year: 1992, Coin Type: Other, Rarity: Common, Country: India, Description: 1 rupee note
