Very nice looking turtle!
I commented on the gravel on your other post.

There was a post not long ago where the turtle died from eating gravel over a period of time. It was a very sad thing that could have been prevented if known by the owner. Turtles are opportunistic eaters - eating anything smaller than them that's put into the tank. This is why it is suggested not to use the gravel.
You should be able to tell the gender of your turtle since it's over 4 inches, thus the questions about the nails and tail. The nails look quite long from the view on one of the pics. Male RES will have very long nails and a longer thicker tail than a female RES with the cloacal opening lower on the tail.
