I recently had to send back 2 Lola Rose bracelets which were faulty. Q sent me 2 pre-paid labels to return them via Royal Mail, so I'm sure they will be fine with you sending them by normal 2nd class with a proof. One time when I did need to send several items of jewellery back I parcelled them all individually, stuck they're labels on, them put them all in one big bag & sent it special delivery. It was about £7/8 & guaranteed next day delivery with £500 compensation for loss. It was fine. Q got them the next day & the refund was issued within a few days.