Thank you, Pareltje, Katbran, kalmen, hanadama, BAS, MSC, BWeaves and Purranha!
I purchased this strand at the same time that I bought the 20" metallic white from day 14. The 20" is rounder and whiter but luster isn't as sharp. It doesn't look very white because it's on a brand new white towel. This 18" strand has strong pink overtones, is not as white as the 20" but has much sharper luster. Back in 2012 I was still very new to pearls and thought I could wear them together. The differences in color were not obvious to me at the time but I really see it now. I had now idea what to say when asked "Do you like silver overtones? Pink?" So I bought both lol!
BWeaves, it does look round on the neck but it's off round. The 20" strand is much rounder. I haven't done a lot of searching but I think it may be a challenge to find the whole package: white, sharp metallic luster, clean surface, round.