Marc,
You ask for comparison weights of copper and silver. Well here is a
list taken from one of my trade books.
1 gram copper = 1.14 grams of silver = 1.53 grams of 14ct gold =
1.73 grams of 18ct yellow gold = 1.80 grams of 18ct white gold = 1.98
grams of 22ct gold = 2.14 grams of fine gold = 2.38 grams of pure
platinum.
A simple way to work out the weight difference between copper and
silver if 1 gram of copper = 1.14 grams of silver then it is a 14%
increase in weight.
I hope this all makes sense, the list was copied from an old Johnson
Mathey bullion book.
Regards from James Miller a goldsmith in the UK