Feb 18, · "The average engagement ring in the U.S. has a center diamond of about one carat and a total carat weight of approximately one and a half carats. An engagement ring around two carats or above would be considered 'big' for the average girl's standards, and anything three carats or above would likely elicit some serious shambhalafundacion.org: Bobby Schuessler. Jun 07, · In the United States, the average engagement ring diamond is somewhere between and carats. However, as we’ve explained above, there are several factors beyond a diamond’s carat weight that affect how impressive and elegant it looks in an engagement ring. Mar 24, · Depending on where you live the average engagement ring size will vary. The carat center stone used to be the most desired size chosen for engagement rings, however, more recently we are seeing this shift towards a slightly larger stone, with couples choosing diamonds averaging to carats. Tip #2: Consider Their LifestyleEstimated Reading Time: 2 mins.