Modern engagement rings are personal, not rule-bound. Compare lab-grown...

https://quebeck-wiki.win/index.php/How_Do_I_Choose_Between_Moissanite_and_Lab-Grown_Diamond_for_an_Ethical_Ring%3F

Modern engagement rings are personal, not rule-bound. Compare lab-grown diamonds and moissanite, see an east-west setting in action, and consider recycled gold