Jason –
What you have described there is a steel-yard!
Their advantage is that if divided accurately they can weigh sizeable masses with only a small reference weight, and very accurately.
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Dave –
Good point. I have no idea now how I thought it is gilding metal, or who told me that.
Although its oxidised colour is very “coppery”, and it still quite pink when cleaned, I did think it is a brass of some sort rather than pure copper when I started sawing the basic square for the ring, from one of the plates. I bought the stuff years ago but this is the first time I have used any of it.
I’ll use it as brass.