Does anyone know if lustre / luster will fade on its own after time.
 
	I know that other items, like curtains or paintings, if left in sunlight will fade.
 
	I make mattresses and I know for a fact that foam goes a darker brown due to the warehouse lights exactly like a sun tan and you can see the "Strap Lines" on the foam where the foam above it has been like a very pronounced shadow.
 
	Coins change due to oil from our fingers so if a coin is untouched and in a cabinet or box which is dark will the lustre fade over time ?
 
	Advise Please !