Hah! No kidding, go to the Galleria on any Saturday, you'll be blinded by the bling!

Certainly Houston, where there's a BMW in every driveway, isn't an average area.
Another thought: How many of those big rocks are the original engagement ring? My real ER was less than a half carat, but ten years and two children later I was rewarded for putting up with him (just kidding, I worship the ground he walks on

) with a gorgeous carat and a quarter.
Anyway, I'm betting there are an awful lot of first rings between 25 and 50 points and that many people upgrade after they became more financially comfortable.
C.