Rachel Koen 20.11 Fancy Deep Brownish Yellow Cushion Cut Diamond Engagement Ring, $325,500
This cushion cut, 20 carat diamond has VVS2 clarity and is GIA-certified, but the description suggests that the diamond's GIA color rating is beyond a Z, meaning it is very yellow, as opposed to clear.
(For reference: Paris Hilton's engagement ring was 20 carats and worth $2 million, but its color rating and clarity were likely far superior.)
The description says the Rachel Koen ring, set in 18k yellow gold, "is all sparkle and shine yet classy to wear every day without looking over the top."