I need to get my hands on some 14k red/rose gold casting grain. Cookson doesn't stock it, anyone know where I can get it?
I need to get my hands on some 14k red/rose gold casting grain. Cookson doesn't stock it, anyone know where I can get it?
Not economical to import it, so best lower your sights and get 9ct red from Cookson. Dennis.
If its for a US customer I just tell them we have 9 or 18 to choose from.
Hi,
Cookson does 9k and 18k in RED so you should be able to mix the two to get 14k.
If I have done my maths right, for every 100g of 18K you need to add 80.288g of 9k
PurA + PurB = 0.375A + 0.750B
A = Weight of 9k
B = Weight of 18k
Pur = 14k/24 = 0.583
If you had 10g 18K then
0.583A + 0.583x10 = 0.375A + 0.750x10
0.583A - 1.67 = 0.375A
0.583A - 0.375A = 1.67
A = 1.67/0.208
A = 8.028g of 9k for every 10g of 18K
Just to check: (0.375 x 8.028 + 10 x 0.75)/ (8.028 + 10)
= 0.583 (14k)
It looks right...but it's late...and I'm tired
I looked at this again this morning and there is a slight rounding error. If you leave all the proportions as fractions the answer gives you 8 precisely.
So the ratio of 18k:9k to give you 14k is precisely 1:0.8 i.e. for every 1g of 18k you need to add 0.8g of 9k.
I forgot we had a mathematician on the forum
I think it can only be hallmarked as 9k though ?
Actually, I made a typo on my spreadsheet.
To get 14k (HALLMARKED QUALITY) @ 585
The Ratio of 18k:9K is 1:0.7857 ie for every 1g of 18k you add 0.7857g of 9k
It's been a long day...
P.S: I'd round down the 9k to 0.78g just to be safe or even 0.7
Thats interesting, I hadn't even noticed they offered a hallmark for that.
Good stuff.
Thanks for the help guys, interesting stuff. I think I'll offer the customer 10k or 18k for now. I'll definitely try experimenting with mixing 18k and 9k to get 14k for the future.
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