It was not plastic surgery but cosmetic dentistry for Crystal, and we need to admit that once we saw her for the first time on the show we knew it was just a matter of time when she was going to get the work done on her teeth. She fixed the gap on her teeth and apparently also got some bleaching procedure to help her have whiter teeth. She looks much better avoiding have all the attention focus on this aspect than on her features or voice.
We think that she may have lost some weight also since her neck looks better defined on the upper angle, and doubt that she got any plastic surgery procedure for now, who knows in the future when she thinks that she may need Crystal would go for it.