I need some help. Did the Elsa Peretti SS mini open heart ever come on an 18" chain (or the buyer having the option to change it from an 16" to 18" in the store)? I bought one of these on eBay and the seller said that it was over 10 years old. The markings all look fine - on the chain and the heart - but the heart just seems better suited for a 16" chain. There are no returns so I'm pretty much stuck with it but I'm disappointed in the length (the seller indicated 16" chain but it's not). Should I be worried it's a fake since it's on a chain that's different from what's on the Tiffany web site (16" on web site for the mini one)?