Part of my degree was specialism in Computational Finance including statistical, financial and economy modelling.
Sounds like I might know a thing or two, I will email you.
I feel the important thing for this is to let it establish its own worth then that can be backed up at a later date.
Say people start buying diamonds for 2 silver each one because they can craft them into something and sell it for 4 silver. Once this becomes a standard (similar to how water and memory stones have become a vaguely standard price) you can make it a standard enforced via other means.