This deal has ended.
Overstock.com drops the 14k Gold 1/2ct TDW Round Diamond Engagement Ring (HI, I1) from $666.99 to $551.99. Better yet, activate the $25 off $500 coupon in this link to cut it to $526.99. With $2.95 shipping, that's $35 less than the lowest price we've ever seen. The color of this diamond is very good (G-H) and it is well reviewed with 5 out of 5 stars from a buyer. It features a round prong set diamond and a pave diamond band. There's no sales tax (except UT).