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How much more does an 18K weigh vs a 14K GF(of say 20/40 microns)

mseamaster
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So I bought a Crown Special that's supposed to be 18K(posted photos in the Seiko subforum). I already had a 14K GF one. I am thinking of comparing their weights. Is that a reasonable approach to ascertain 18K? I just need to get a tool to remove the strap on the 18K and then I will measure.
 
X350 XJR
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Unless the construction of the two cases are exactly the same, e.g., wall thickness etc then no, you are comparing apples to oranges.
 
mseamaster
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It does look the same save for the caseback which looks different. Can't say anything about thickness.
 
Dan S
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The weight difference of a gold filled case will be insignificant. You’d need to do an acid test. But honestly I can’t imagine why it would matter for a gold filled case.
 
Dan S
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Incidentally I don’t think any of these watches came in solid gold cases, just gold filled and gold capped. But do your research and have it tested. I’d start by looking at the inside of the case. Weighing is is pointless.
 
mseamaster
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What about having a watchmaker disassemble the watch, take the case, calculate its volume by submerging it in water, weighing it and comparing the density to that of 18K?(which I expect could vary depending on what's added to the 75% of gold)

Would such a test be useful?
 
Davidt
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I can’t see what use or benefit there would be from such a test.
 
mseamaster
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The benefit would be that at least in theory the case should have a density(grams/m3) of 18K and not say brass with gold filling. I take it, gold is much heavier so it should be discernable. I think Seiko probably used the same type of 18K, so perhaps the density is published somewhere.

Another question I was just thinking about: are the dials on 18K vintage Seiko made from gold too? Or is the same dial used on 14K gf/18k? I am not talking specifically about the Crown Special but in general. I never had clarity on this tbh.
 
Dan S
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Have you even looked at the inside of the case? Or would you rather just speculate about overly elaborate testing methods? It will probably be clearly marked.
 
mseamaster
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Will post again when I get time to bring it to a watchmaker. I am super curious because normal Crown Special's are GF and this would be interesting if turns out really to be 18K.

I asked about the dial material because the current dial I have is the basic one. I wouldn't mind replacing it with the special one from a GF Crown Special.. but only if the material is the same. I don't like frankenwatches.
 
GTveloce
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Dan S Dan S
Have you even looked at the inside of the case? Or would you rather just speculate about overly elaborate testing methods? It will probably be clearly marked.
Exactly what I was thinking shouldn't there be a hallmark on the case if it's solid gold regardless of karats?
Even heavily polished cases should still have clear traces of the hallmark.
 
mseamaster
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GTveloce GTveloce
Exactly what I was thinking shouldn't there be a hallmark on the case if it's solid gold regardless of karats?
Even heavily polished cases should still have clear traces of the hallmark.
There's an 18K wrriten on the back. But I couldn't find any hallmark whatsoever. I will look again with a magnifier.
 
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