Large plastic cigar tubes, Cohiba size, are great for carrying large amounts of uncut diamonds and do not trigger metal detectors — as a pocket full of Krugerrands would — and allow for sizable amounts of non-bank-held assets to be stored in a secure location.
As long as there are women, there will always be a demand for diamonds.
I personally like collecting Gems of the Bible, with the relevant chapters and verse displayed along with them.
http://www.preciousstonesofthebible.com/stonegallery.html
The people pillaged, slaved, for gems is astounding