I bought this as a set to go "out out" with, as this is when my jewellery tends to go missing or get damaged! My actual engagement ring is .75 ct so I reckon this centre stone might be around 1.25 equivalent? Maybe Adam can clarify, as there is no measurement in the description. In my opinion any bigger than this (1 ct equivalent is probably best) and you loose the believability that it's real at first glance, albeit excellent quality. If that isn't a concern then I very much doubt you will find anything as striking and as well made as this for the price anywhere else. I would not hesitate to buy more, I already have more pieces in my basket! Customer care and ring set are both superb.