I bought a class 1 100 gram weight like a good boy. That said I don't think it really matters what class weight you use as long as you keep it clean and and dust free.
Even if your calibration weight is a full gram off it won't matter for reloading, weighing gold or chemicals yes, powder no. Why would I say such a foolish thing?
The scale will still have the .001 gram capabilities, even though you tell it to weight out 100 grains and it actually weighs out for example 99.82 grains it doesn't matter. You are going to work up your load and use whatever charge your gun likes. The number is just a reference number that is repeatable by the scales capability.
When I weighed out on a beam scale I used calibration weights and balanced the scale using calibration weights as close to the charge weight as I planned on using or where I thought I would end up. Once I got my FX120i I found out my calibration weights were .2 grains off but the gun didn't know the difference. I found a charge weight the gun liked and that was that.
So I think the scales repeatability is much more important than the weight you use to calibrate it for the purpose of reloading. Legal trade of silver or gold is another story.
