Yes, 530 BCE is 'way before Plato's time, and we have no idea who the artist was.  'Tis a bit of a stretch to call it Platonic art.  But there is a painted statue in the Republic (Book 4, 420cd):
 

Suppose that we were painting a statue, and some one came up to us and said, "Why do you not put the most beautiful colours on the most beautiful parts of the body -- the eyes ought to be purple, but you have made them black!"  To him we might fairly answer, "Surely, you would not have us beautify the eyes so much that they are no longer eyes; instead, consider  whether, by giving the eyes and the other parts proper treatment, we are making the statue as a whole beautiful."

And Socrates goes on to compare the beauty of the statue to the happiness of his ideal city.

Click here to see the Peplos Kore statue - be sure to scroll down the page to see the re-creation!