Roughly how much would it cost to replace a diamond with a ruby in an engagement ring?

Being a dumb guy on these matters, I would estimate the size to be roughly 3/16th inch. There are diamond flakes surrounding the center stone. Any help would be greatly appreciated. ThanksRoughly how much would it cost to replace a diamond with a ruby in an engagement ring?
go ask a jeweller - a great ruby actually costs more than a great diamond because very good quality rubies are rarer than very good quality diamonds.for a fantastic ruby,you need to be looking for blood red - most rubies sold for general jewellery purposes are more pink