When ordering rings online it is the customer’s responsibility to ensure they have ordered the correct size.
The most accurate way of establishing your ring size is to visit a local jeweller for measurement, and importantly, stating the width of the ring that you would like.
The best time to have your ring size measured is when you are warm, and in the afternoon. Your finger measurement can otherwise be too small if it is cold, or if you have not had much physical activity on that day.