Can someone please help me… I’m baking my noodle!
I have 3g of customers own 9ct gold and I need to bring it up to 18ct.
If my 3g of 9ct is 37.5% gold then it contains 1.125g fine gold & 1.875g of presumably copper and fine silver.
I normally alloy 18ct at 75% Gold, 15% copper and 10% silver
How much fine gold do I need to add to bring it up to 18ct? Do I need to add extra copper & silver?
I have alloyed gold before but never this way round and I’m going round in circles trying to do the maths!