MGH
Well-known member
Hi all,
I bought some scrap yesterday and ran across this watch case. The inside is marked "14K". The top half, not picture, was more ornamental, white gold color, and behaved as expected with an acid test on a scratch stone. This bottom half is much harder, and I can't even get a mark to rub off onto the stone. I thought it might be a stainless steel back, but strange that this is the part marked "14K". The seller agreed to let me take it, run some XRF testing, and do more research.
Stranger still are the XRF readings shown below. The XRF does see a significant amount of gold, but the alloyed components aren't as expected. I measured the back and inside, with two different methods on the XRF.
- The back is reading as ~44% Gold, with ~25% Chromium
- The inside is reading as ~53% Gold, ~20% Copper, ~5% Chromium
- The above trends in the readings were very similar whether using a general "Alloys" method or a "Precious Metals" method (I did measure the inside with a PM method, just forgot to get a picture)
The reading showing 25% Chromium was the first scan I took. This composition was unexpected, but I thought maybe that could explain the hardness and inability to make a mark on the stone. But then the inside reads very differently, with much less Chromium. I can't tell if this is all one stamped piece, or possibly three pieces together (outside-back, side, inside-back).
Any ideas? Has anyone seen this before? Is there an explanation why this metal is so much harder than typical 14K? Is there a reason an XRF would think there's chromium in a gold watch case? Should I stop overthinking it, and just pay for the scrap?
Thanks.
I bought some scrap yesterday and ran across this watch case. The inside is marked "14K". The top half, not picture, was more ornamental, white gold color, and behaved as expected with an acid test on a scratch stone. This bottom half is much harder, and I can't even get a mark to rub off onto the stone. I thought it might be a stainless steel back, but strange that this is the part marked "14K". The seller agreed to let me take it, run some XRF testing, and do more research.
Stranger still are the XRF readings shown below. The XRF does see a significant amount of gold, but the alloyed components aren't as expected. I measured the back and inside, with two different methods on the XRF.
- The back is reading as ~44% Gold, with ~25% Chromium
- The inside is reading as ~53% Gold, ~20% Copper, ~5% Chromium
- The above trends in the readings were very similar whether using a general "Alloys" method or a "Precious Metals" method (I did measure the inside with a PM method, just forgot to get a picture)
The reading showing 25% Chromium was the first scan I took. This composition was unexpected, but I thought maybe that could explain the hardness and inability to make a mark on the stone. But then the inside reads very differently, with much less Chromium. I can't tell if this is all one stamped piece, or possibly three pieces together (outside-back, side, inside-back).
Any ideas? Has anyone seen this before? Is there an explanation why this metal is so much harder than typical 14K? Is there a reason an XRF would think there's chromium in a gold watch case? Should I stop overthinking it, and just pay for the scrap?
Thanks.