For newbies who do G.F.

[Emryst]

I've seen a couple post here asking what the expected yield should be for gold filled jewelry. I just wanted to show some calculations I did on a small batch of 53.11 grams i had. To prove the constant of .025 works.

G.F. is 5% of total weight in plating. Of that 5% your calculate for karat type to get pure gold content. i.e. 14k of 10 grams G.F. is .5 grams of 14k and of course that would be .29 grams of gold in that 10 grams.

So if you take that same 10 grams times .025 it's an easy calculation at .25 grams of gold.

Even with mixed karat G.F. It works. My small batch calculations will show.

10k 13.97g x .05 x .417 = .29
12k 30.84g x .05 x .5 = .77
14k 1.36g x .05 x .583 = .039
18k 6.94 x .05 x .75 = .26
Tot - 53.11g 1.359g gold

53.11g x .025 = 1.32g gold.

Im thinking most have already figured this out but I wanted to put this here so others who don't will see.

Edit added text: keep in mind if your buying from ebay it's usually not stripped of gems and stainless e.g. watch bands, watch guts. So your gonna have to do a guesstimate on proper weight not what's posted in ad.

 

[Yggdrasil]

I've seen a couple post here asking what the expected yield should be for gold filled jewelry. I just wanted to show some calculations I did on a small batch of 53.11 grams i had. To prove the constant of .025 works.

G.F. is 5% of total weight in plating. Of that 5% your calculate for karat type to get pure gold content. i.e. 14k of 10 grams G.F. is .5 grams of 14k and of course that would be .29 grams of gold in that 10 grams.

So if you take that same 10 grams times .025 it's an easy calculation at .25 grams of gold.

Even with mixed karat G.F. It works. My small batch calculations will show.

10k 13.97g x .05 x .417 = .29
12k 30.84g x .05 x .5 = .77
14k 1.36g x .05 x .583 = .039
18k 6.94 x .05 x .75 = .26
Tot - 53.11g 1.359g gold

53.11g x .025 = 1.32g gold.

Im thinking most have already figured this out but I wanted to put this here so others who don't will see.

Edit added text: keep in mind if your buying from ebay it's usually not stripped of gems and stainless i.e. watch bands. So your gonna have to do a guesstimate on proper weight not what's posted in ad.

You cant do it like this.
There are 10, 12, 14 and so on karat.
There are also 1/20 or 1/10 thickness.
So depending of the kind of GF it may be almost correct or totally wrong.

 

[Hartbar]

There are some old pocket watch cases that give you much higher yields.
The kind that don’t state 1/10, 1/20. 10k or 14k,.They just say gurenteed 20 years, I’ve seen these yield 5 to 7%.

 

[Shark]

Those watches marked guaranteed are the markings. I don't recall right off but 20 years and 25 years designate different values such as 1/10 10k or 1/10 14K for example the longer the guarantee the more gold it contains.

 

[macfixer01]

You cant do it like this.
There are 10, 12, 14 and so on karat.
There are also 1/20 or 1/10 thickness.
So depending of the kind of GF it may be almost correct or totally wrong.

I agree you can’t do it like that in any case, and there is no “one size fits all” formula. FYI though it’s even more variable since I’ve seen all the way from 1/40 down to 1/5. Also the amount of wear makes a big difference between for example one pocket watch that was never used, and another which obviously has brass showing through the surface.

 

[Emryst]

You cant do it like this.
There are 10, 12, 14 and so on karat.
There are also 1/20 or 1/10 thickness.
So depending of the kind of GF it may be almost correct or totally wrong.

The main point was the constant will get u close to an expected yield. But yes you are correct i was not factoring in 1/10 1/20. As stated in was only talking about 1/20th G.F. I haven't actually seen much 1/10th or 1/30th for that matter so far. At least not marked. But I’ve only run thru about 20 lbs so far of jewelry in my short time refining hobby.

 

[Shark]

Having a price point that your comfortable/confident with is good. I have used a fixed point for several years that I know will be profitable and not feel like I am robbing the seller. My plan has always been to look for repeat customers be they buyer or seller. It has worked well for me for a long time.