Fair enough, I think the original medal ribbon is referred to as “watered silk” which is how the ribbons have that shimmer when you move them.
The modern replica ribbon doesn’t have it so it looks cheap in comparison, as below...
Hmm, well let me be clear. If you are referring to the original ribbon on the original medal then I would agree, 100 years on and its going to have aged. That said if the medals have been well looked after then the ribbons can still have their original lustre, and wouldn’t need to be replaced...
A mate of my (sadly now deceased) used to buy and sell WW1 medals, he would typically buy a set then investigate providence of the individual and then create a framed presentation, typically with pictures of the individual, regimental badge and copies of records of service etc. For collectors...