While copper sulphate is somewhat poisonous, and sulfur is what reacts
inert substance. You may want your copper bracelet to 'antique'
mostly copper sulfide (black stuff)

-- "rather than copper sulphate (blue-green stuff)" --

And, what most people (at least the people I know) are allergic to
isn't copper but the cobalt and nickel that's usually in it.
One of my reasons to prefer surgical steel earring hooks over sterling
silver - but I know a person who's allergic to those too.

It depends on whether you're after the shiny appearance or what
else you're after.

Just a small interruption if anyine is interested--

The blue-green coating usually forming on copper exposed to the weather is
basic copper carbonate, sometimes called "verdegris", not copper sulphate
which is a crystalline solid.
(granted, it is blue-green.)
Copper sulphate is water-soluble and would wash away from the metal surface
when it rains, if it were to form.
I am not sure of the mechanism which causes some wearers of copper jewellery
to get greenish stains on the skin, it is probable that ammonia or an amine
in the sweat allows copper ions to penetrate the skin..

-- end of interruption.

G.H.Ireland

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