NCIS: Sydney backdrop

NCIS: Sydney S3E18 — Rough Diamond

7.6

NCIS: Sydney•Season 3•Episode 18

Rough Diamond

7.6/10 · 157 votesMay 5, 202641 min

Ranked #18 of 20 in Season 3•−0.2 vs season avg

The death of a former Marine wanted for murder leads the team to a sinister plot involving a disgraced journalist, one of Australia’s richest men and lab-grown diamonds.

Previous episodeE17 · Flight Club Next episodeE19 · Hunter

Seasons4

Cast7

Olivia Swann

Olivia Swann

Michelle Mackey

Todd Lasance

Todd Lasance

Jim 'JD' Dempsey

Sean Sagar

Sean Sagar

DeShawn Jackson

Tuuli Narkle

Tuuli Narkle

Evie Cooper

Mavournee Hazel

Mavournee Hazel

Bluebird 'Blue' Gleeson

William McInnes

William McInnes

Dr. Roy Penrose

Claude Jabbour

Claude Jabbour

Travis 'Trigger' Riggs

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Episode Summary

"Rough Diamond" is episode 18 of NCIS: Sydney season 3. It scored 7.6/10 from 157 votes, ranking #18 of 20 episodes this season (season average 7.8). It aired on May 5, 2026.

Next: E19 · Hunter Best of Season 3