I think on another feed someone was talking about a packaging thing causing rashes and not the actual necklace itself, it is also possible that that is what is causing the “plastic-y” feeling too. I think it is way more likely that some chemical from packaging that is left on the necklace is causing a rash than the metal itself, especially considering you can wear cartier things.
I honestly have never had this issue, but i’ve only gotten things from boutiques. I own a little cartier, and I find their chains much more fragile and less substantial than VCA. I also find their rg to be more susceptible to oxidation. I prefer VCA clasps and actually as a whole find their jewelry and watches to be higher quality. I don’t wear my cartier pieces everyday (caresse d’orchidees wg pave pendant, rainbow love, trinity bracelet, diamants légers pendant and bracelet) because I honestly think they look cheaper than VCA (particularly due to chain/the love being a lot less intricate of a design).
However, my opinion, or anyone else’s on this forum for that matter, cannot outweigh yours in regards to a purchase that you are making or have made. If you don’t like it, return it. If you want to try another metal from VCA or not, do that. Same thing with a different stone. In general, if you’re not in love with it every time you see it it’s probably not the piece for you and you would be better off saving or investing the money in something else.
General Advice: I will say that nearly everyone on this forum will say that you cannot adequately determine if something looks good on you if you haven’t seen it in person and ON you. Things look different on a tray than on skin. They especially look different from photos to real life.
I always buy in person. This is even more important when you’re considering stones that have significant color or striation differences amongst pieces (pretty much everything but pave diamonds and onyx). Even if you have to order something and wait to get it in boutique, it is more likely that you will be satisfied with it then after seeing it on and comparing different metal colors and stones. remember—this is likely going to be a piece you own for a while, so waiting a short period of time in the beginning is way better than having buyers remorse. It is so hard to say from photos if one stone or metal type will look good on you.