Size and weight variation.

Hi All.

I am developing a Jewelry/Jewellery site.
I can do variables for ring size no problem.(G-Z+3 with 1/2 sizes)
It gets complicated however when as the size increases so does the weight and therefore expense.
Anyone have suggestions how to handle this without having to amend each of the 46 variations as one group or individually.
I tried doing 3 groups but of course the client could choose one of each group in a single purchase.
Even if I could bulk change just groups of the variations instead of all of them at once that would be ok. Like…just variations 30 – 46.(for the larger sizes)

TIA.
Darren.