Loop with "for" and "if" and then a scatter-plot with different colors

Question

I would like a scatter plot with two different colors for different fields.

I have one table with x1, x2, y3. I make one scatter with scatter(x1,x2,"o","filled"), but I would like that colors were on the base of y3.

y3 has values from 0 to 81. I would like that fields with values<10 were green, vice versa values>10 were red.