looking to upgrade my wife''s 11 year old ering and wedding band - looking for something in the 1.5 - 1.75 range - probably a G or H - VS2/eye clean SI1 - and just trying to get my legs under me with all this - so I like the HCA as a great guide - is there really any discernible visual difference between say a HCA score of 1.3 and 1.8?