is the 목걸이 blair wears in 4x02 the same as the one Chuck gave her in 3x18?

I think the 목걸이 is different...

Nope it's not the same, but they do look similar from that screenshot 당신 got from 4x02. The 목걸이 in 3x18 was from Cartier, but the one from 4x02 was from Harry Winston.