It can be challenging to figure out your partner’s ring size, without them knowing what you’re up to. If your partner wears rings, start by measuring the inner diameter of one of their rings with a vernier caliper – that will give you the most precise measurement to use to figure out the size. You can also bring the rings to a local jeweller and ask them to check the size. Just be sure to note which finger she or he is using the ring on – our fingers have each their different size, and the sizes even vary from left to right hand.
Sometimes asking their friends or family can help – they might know or have an idea of the size.