Mr W
Guineas date from the reign of Charles 11 1663 and finished during the reign of George 111 in 1798 . Originally they were what we now call a pound but many years after introduction as the value of gold changed they became 21/-. Obviously they trade at huge premium to the Gold content as they are coins of interest to numismatists. The point I was trying to make is that high quality historical Gold coins have performed extremely well over the last five years, just to give an example taking the same coin an extremely fine Giunea dated 1666 in 2000 it would have sold for around 1,750 would now fetch around 6,000.I have oversimplified by choosing just one item but most sectors of the collector coin market are alight. Extremely rare items are breaking records all the time. One of the more extreme examples last year was an extremely rare Triple Unite ( 3 pound gold coin) dating from 1643 which had an auction estimate of $100K to $120K fetched $430k.
Hope this helps.