It certainly IS a very pretty little turtle, but I don't think its a RES. They don't usually have such a pronounced keel (if that's what you call the ridge on the back).
It is a RES. You just don't notice the keel because of all the pattern that is normally there. The patternless morphs will play tricks on you sometimes, making you think the keel, legs, face don't look quite like a RES, but I assure you this is a Caramel RES.
If a morph like this popped out of another species, you could rest assured the morph breeder that produced it would highlight exactly what it was to get every last dollar out of their prospective buyers.