Can you help my diamond?

Hi I have a few questions regarding treating a diamond ring my fiancé purchased. I will include a photo and specifics about the diamond. The center stone is 2.40 carats oval diamond with an H-I color and I1 clarity. What can your services do to improve the color and clarity of the diamond?
What will this cost? Can the small round stones on the setting be improved with treating as well? If color is desired is it possible to give color to the diamonds through "treating" the stones? Lastly, how long does it take to return the items once treated? Thank you for your time."

Gypsy D.

All great questions. Please visit Leshem.com Q & A for more information.