I don't understand how the jewels sentence is not necessary but it is sufficient. I get that it is not as narrowly tailored, but diamonds still fit into the category of jewels so that sentence still applies to them. I feel like the way this concept was explained went completely over my head. I understood everything until that point where it was sufficient but not necessary yet still applicable to diamonds because diamonds are jewels. Unless my problem is that I made the assumption that all diamonds are jewels.

This felt very similar to rule and stimulus application questions. am I wrong to make this connection?

Sometimes wrong answers are glossed over as just wrong without much explanation as to why or how the potential reasoning that might guide you there is wrong. This would be helpful in correcting what we might be doing wrong in Logic strategy or any rules we might have missed. I miss a lot of answers by getting confused with the contrapositive but then those possible confusions are never addressed. The video instructors simply say something along the lines of "this answer is obviously wrong," but to us starting out it does not feel so obvious as to why.