you have a combination of possibilities here.
1). take the bracelets to cartier and verify under the serial code what color gold is made for that piece. (however, just because it's a match doesn't mean it's authentic either as it can be replicated)
2). is your yg love a new or old screw system? I find that the older screw systems yg seems to be slightly more yellow than the newer ones. (or it can be the metal oxidizing causing a deeper yellow hue, sometimes a steam or ultrasonic cleaning helps with that)
3). your yg juc does look more like a pale yellow compared to the love. I don't see any pink in your juc, my pg juc has faded but there's definitely a hint of pink compared to my yg love and I don't see that in your juc at all. (however, Cartier's pg has been known to fade quite a bit and for some people, their pieces have turned pretty much yellow, so it's hard to say yours didn't)
4). all in all, there's nothing wrong with purchasing pre-owned. However, there are so many well replicated Cartier jewelry out there (especially love line), that it does make you question the authenticity. I don't personally have experience in purchasing pre-owned, but I know that for a lot of people, once you question the piece you have, you always will.
With all the headaches that comes with buying pre-owned, I recommend purchasing directly from the store, as you know what you have is the real thing.