Ive seen res really odd in color. Im not kidding, back in the day when they were readly traded here, IVE SEEN BABY ONES THAT WERE BLUEISH IN COLOR! Had some of those, they completly loose all of it, in adults they are darker in color. A person that is a diamont back terrapin breeder has some reddish ones! In the future I can see some really cool new morphs being created, as people cross and perfect random mutations.
They are a fun turt to keep, just make shure that the color is natural and not from some hillness they may have.