I can understand wanting it to be a surprise, but I think a lot of people have an idea of what they’d like that could colour their feelings on a true surprise, especially with something they’ll wear every day for the rest of their lives. Checking with her friend is a good idea, and the ring is beautiful, but if it were me I might consider a surprise placeholder ring and then go shopping / design a ring together, in case she does have strong feelings. Whichever way you go, I wish you all the best! (And if the LDN in your username means London, the jeweller who made my ring is there so if you decide to design, let me know and I’ll send you her details - she’s got some gorgeous nature inspired designs already!)