One of the trickiest parts men find when it comes to buying engagement rings is that they don’t know what size to buy. Unless you’ve bought your girlfriend another ring previously, or been present and paying attention when she bought one for herself, the chances are you’re not going to know the size already. Plus, even if you have already bought her a ring, was it for the left ring finger? We think not. Finding out the ring size without ruining the surprise so you can go shopping for diamond rings in confidence isn’t easy, but here are our tips.

Asking her to try on another ring on that particular finger for a made up reason is far too obvious so forget that straightaway. One of the best ways to keep the secret is to get her best friend, sister or mother involved. Women frequently visit jewellers shops “just to have a look”, so a bit of clever engineering can get you the size without her ever realising.

There is also the old trick of using a piece of string while she’s sleeping – just make sure she’s a heavy sleeper first! Should you still not be sure, you can of course always get a ring resized up or down. When buying quality rings such as diamond solitaire rings, it is advisable to aim for too small rather than too large as it is easier to size them up. The average size for ladies in the UK is ‘M’ or ‘N’.