Haven't read the police re AP and jewellery since the advent of click & send as I don't sell fine jewellery but back then registered post, with extra cover, had to be used if you wanted to be compensated for a lost parcel.

Once you start adding extra cover there is little difference between the cost of reg post and c&s anyway.

Totally correct though that you never send anything that you are not prepared to refund or replace without question if the buyer says it has gone missing by regular parcel, express satchel or red satchel, the tracking on those is not up to Paypal requirements.