How much is a piece worth?

One of the more attractive, yet frustrating parts about chess is that the most interesting games are the ones where the normal 'rules' are broken. We jealously guard our pieces, up until we decide to sacrifice them, understanding that the side with the stronger army doesn't always win. While knowing when to 'break the rules' is normal for experienced players, it can be very confusing for new players.
But knowing when to take a piece can even be tricky for GM's. The first day of the GCT Rapid in Belgium saw a stark example of this in the Giri - Aronian game. Giri left his knight on the edge of the board as bait for Aronian, who decided to trap it with 8. ... g5. White Giri got in return was not an immediate win, but a lead in development and a strong enough attack that Aronian was only able to avoid mate by eventually returning more material than was initially captured.


Giri,A (2771) - Aronian,L (2793) [A29]
GCT Rapid YourNextMove Leuven BEL (3), 28.06.2017