Diamonds - an Investor's best friend?

Just finished watching a clip on one of the major financial news channels. They discussed the benefits of investing in diamonds. At a time when the tax levels in all major industrial nations approach confiscatory levels and more of the same might be in the cards (tax on all cash holdings and bank deposits in the shape of 'negative interest' rates, - watch this space!) the portability and durability of the gems might appear to be a major advantage. But - as always - the devil is in the detail. The promoter who was interviewed on the programme correctly pointed out that there are innumerable categories of diamonds and that the (wholesale) pricing of the stones is only transparent for professionals active in the diamond trade. Retail customers and investors have no option but to use highstreet shops that charge high mark-ups. This will leave the investor out of pocket if ever he wants to sell his holdings. In addition to the loss due to this 'spread' he will also be exposed to the vagaries of a volatile market which could add to any potential losses. Guarantees that are offered attached to various 'investment schemes' should be taken with a (very large) pinch of salt, or better, ignored completely. It is usually less than clear who is ultimately backing these guarantees and what the financial standing of the guarantor is (or under what jurisdiction the guarantee can be called upon).