12ct gold

[ps_bond]

It's a traditional Japanese alloy, 96% copper and 4% gold. Patinates to a lovely rich purply-black.

[SteveLAO]

Of course your other option would be to reduce your 12ct down to 9ct. On the basis that if you submitted your 12ct gold you'd only get a 9ct hallmark, why not increase the overall weight of the alloy and make something heavier with 9ct gold?

So your 10g of 12ct (0.500ppt) would give you 5g of gold and 5g of other metals. You would have to add another apx 3.4g of other metal to bring your overall total weight up to 13.4g of alloy. 13.4g of 9ct gold (0.375ppt) would contain apx 5.0g pure gold and apx 8.4g other metals which would be a 9ct pass for assay and hallmarking. (figures are apx.......!!)

You'd have to look as to whether it is worth it for an extra 3.5g though. Your finished item would either be 10g of 12ct which you have to sell as 9ct, or 13.5g of 9ct less the cost of remixing....