Good cards, Bad turn

[MD_]

For EP, the preflop action suggests a pocket pair, and the postflop action suggests a set or 88 for a straight. UTG could have all of the above plus two big diamonds. Since you have the nut diamond, I don't think you're in danger of a 3rd bet. Just call. I'd plan on folding the river UI. Of course, I usually change my read to something I can beat when I'm faced with a bet on the river.

-MD