Laser tech unlocks the Ti-sapphire item, which needs diamonds to craft, but it doesn't need the diamond tech as a prereq.

I've fixed this. I've changed it so Laser tech always requires diamond processing tech, whether or not Ti is enabled. I think the tree works well both ways, and it keeps it simpler this way.

Necro: diamond tech can be unlocked before you unlock the machine that you use to make it.

Thank you once again. Keeping me honest :)

Upcoming release will have a small tweak to the tech tree to fix this, and also to not require diamond processing for production science pack tech. Should be a slightly smoother tech tree.