need to know raising 1OZ of 10kt to 1 OZ of 18kt.
For 1oz of 10k you should add 1.35oz of 24k to raise the 1 oz of 10k
to 2.35oz of 18k (actually 75.1%)
I have created a simple spreadsheet that works this out for you on
the fly - let me know if it would be of use and I will post a link.
If you want to work it out on paper
1g of 10k = 0.42g gold and 0.58g alloy
The only thing you want to change is the gold content so the alloy
weight stays the same.
18k is 75% gold so if the alloy is 25% at 0.58g, the gold content
must be three times this (3 x 0.58g = 1.75g)
The new mix will be 1.75g gold and 0.58g alloy - total weight =2.33g
You already had 0.42g of gold in the original 10k mix so 1.75g -
0.42g = 1.33g
Then it would be wise to add a smidge more gold to ensure that the
resulting alloy passes the required 75% margin.