According to the chart, there's two green gems in part 5 and one in part 6. There's actually two green gems in part 6, and I don't recall there being any green gems in part 5, unless I'm missing something. -- 16:01, 4 October 2019 (CEST)
Actually, disregard this. I was mixing up part 4 and thought it was part 5, I forgot that the highway is part 6. -- 16:15, 4 October 2019 (CEST)