...That fits into a suitcase. Granted, it's too heavy to carry...
At current prices, $10 million in gold are 12,574 troy ounces.
If you have 400 oz bars, it takes 31.4 bars.
1 400 oz bar is 200mm x 80mm x 45mm
If you arrange the bars like six packs and stack 5 on top of one another, you can arrange 40 bars in the following space
200mm * 3 = 600 mm = 22. 62 inches length
80mm * 2 = 160 mm = 6.3 inches width
45mm * 5 = 225 mm = 8.9 inches height
( source for the dimensions of bars: http://www.taxfreegold.co.uk/goldbardimensions.html )
That fits into a suitcase. Granted, it's too heavy to carry as these are 0.391 tonnes or 862 pounds.
While it makes gold less portable than diamonds, a car can easily carry such a load. Gold's uniformity may be more important than a diamond that needs to rely on certificates.
If you can afford it, you may want to carry a stack of both - and don't forget some gold coins as you are unlikely to get any change if fiat money is no longer accepted.
Manager of the Merk Hard Currency Fund, http://www.merkfund.com/