What's the Name of That Book??? discussion

The book is about a girl trying to finish a scavenger hunt-style game to win an inheritance. It's a competition between multiple people/families.
I only remember a couple of the challenges:
-they have to mine a diamond from a real diamond mine. The group that wins is disqualified for pretending to find a perfectly polished diamond
-they need to find a certain antique that was at the dead man's house, and take a picture with it. earlier in the book, she had taken a picture of the antique and she shows up in the reflection, and wins the game

I read it sometime around 2017-2020

The 39 Clues series by Rick Riordan has a girl and boy taking part in some sort of scavenger hunt-type competition against their families to win an inheritance, but I only read the first book and have no idea if either of the two scenes you listed is in it.

This sounds like Inherit Midnight -- reviews mention the diamond mine.

Stephanie wrote: "This sounds like Inherit Midnight -- reviews mention the diamond mine."

This is the one! Thank you!