How would I change the border color of a button?

This is my code:

buttonName = "btn" + y.ToString() + x.ToString();
Control btn = this.Controls.Find(buttonName, true)[0] as Control;
btn.BackColor = System.Drawing.Color.Blue;

However, I see no border color changing properties, or the like.

I used this code because I have a lot of buttons on my form, and any of those buttons' properties can change, so rather than call them out individually, I just made up that code which could handle them.

Is there a code similar to the one above, that would allow me to change the border color of the button?