The first and most obvious thing that any coin collector will tell you about their treasured discs is that they need to be looked after, and certainly never dropped as the cracks and bruises will never heal.
But in Australia right now, there are a couple of coins which will derive most of their value from being dropped - after being flung up in the air, no less.
The coins in question are two special release AU$1 coins set to be used for the toss at the Australian Open tennis tournament.
One features the Daphne Akhurst Memorial Cup - the trophy awarded to the women's singles champion, whilst the other features the Norman Brookes Challenge Cup, awarded to the men's singles champion.
The auction, taking place on eBay, will close in the evening (Australian time) on January 31. At the moment the men's coin has reached AU $202.50, whilst the women's coin languishes on its default bid of 99c (something of a bargain for a $1 coin).
No doubt both will increase substantially, but there might be a reason beyond sexism why the men's coin will do better: 2012 is the hundredth Australian Open men's singles championship.
How well will they do? Well, last year saw the sale of 'toss coins' for the cricket world cup go on sale. These ranged from the modest price of $350 for New Zealand vs Kenya up through an impressive $10,300 for the spectacular England vs India tied match up to a startling $100,200 for the India vs Sri Lanka final.
There was an additional value to that coin of course in that there was a huge controversy about its having to be re-tossed when the match referee did not hear the call.
It's unlikely that the tennis coins will do as well as that, but perhaps it will depend in part on whether Nadal, Murray or Djokovic wins the final. Watch this space for the result.
Collectors may also be keen to know that we have a signed photo of Andy Murray available. We've already sold a tennis ball signed by Nadal, Djokovic and Federer, so it may not be around for long!