We can see many deals being offered at different auctions sites, offering us anywhere from scrap Gold Filled (GF) watch cases/bands to pins and other decorative ornaments. In many cases a confusing or plain wrong weight measurements are used to describe the items in order to get the buyer to base his calculations on inflated numbers. This article was written to prevent that.
We should probably get familiar first with the known Gold Filled standards and how it's made: Basically and without going through the entire production process, Gold Filled is a thin sheet of karat gold (10K, 12K and 14K) which is fused to a thicker sheet made out of base metals of different alloys such as Brass/Bronze. Sterling Silver is also used, though less common. The process usually involves rolling the two sheets together to a desired thickness (hence the synonym: Rolled gold). Together, these sheets are formed into fairly rigid, hollow shapes and enjoy a protective cover (and looks) of a noble alloy but at a fraction of the price of an actual Gold jewelry.
1/20 12K - What is that??
The first numbers (1/20) indicate the ratio between the mass of the Karat Gold sheet to the mass of the entire piece (karat + base metal) at any given dimensions of the Gold filled sheet. Clarification: Surface area does not play a part for calculating Gold Filled value. Whatever size or shape you cut the Gold Filled sheet, the ratio by mass remains the same. The second number indicates the karatage of the Gold sheet alloy. Now, say we want to know how much actual gold is there in a sheet of Gold Filled. Example: How much gold would there be in a 100g stamped sheet of "1/20 12K" Gold filled?
1/20 = 0.05 (or 5%) 100g x 0.05 = 5g 12K = 12/24 = 0.5 (or 50%) 5g x 0.5 = 2.5g The answer will be: 2.5g of pure gold. These are the exact steps our calculator use. But wait, keep reading… Mainly, there are three agreed mass ratios of which a sheet of gold would be considered as Gold Filled. Minimal karat should be of 10K. 1/5 - 10K , 12K , 14K 1/10 - 10K , 12K , 14K 1/20 - 10K , 12K , 14K Though 9K pieces are not officially recognized as Gold Filled, it is very common to find that kind of jewelry circulating around and stamped as GF scrap. Any figure above 1/20 (at any karat) will not be considered as Gold filled as well, it is now called Rolled Gold Plate (R.G.P) or Heavy Gold Plate (HGE) and usually is marked that way. The known gold to base metals ratios for R.G.P are: 1/40 and 1/50 Karat ranges from 10K to 18K Note: 18K Gold Filled is not common in many countries. Had it been offered to you, it will be wise of you to suspect it to be R.G.P rather then Gold Filled. The calculation remains the same though.
From theory to practice.
Calculating the value of Gold Filled scrap based on known standards is fine and can give you an idea of theoretical value. Why theoretical? Since in real life, we have to consider the fact that the Gold Filled Scrap is what it is – Scrap! An old and used item. Meaning the gold layer will suffer from surface wear or even peeling of the gold layer in some cases.
Sometimes pieces of Gold Filled are soldered together, the solder adds weight of base metals to the piece and effecting the standard gold to base metals ratio.
Surface wear can easily count for a reduction of yield by 10-20% (and even more) than the theoretical calculation. Always try to notice the surface and estimate the wear. Items with excessive surface wear should be refused. Another very important point you should know is, that the Gold Filled calculation relates only to those parts that are Gold Filled and not the entire jewelry piece. For example, a pocket watches can have a GF casing but the entire mechanism inside is not. Therefor the mechanism should not be included in your calculation... Otherwise, you will pay gold prices for Stainless steel. There are many jewelry types with variety of structural related items which are not Gold Filled and should be excluded prior to calculating the Gold value. You may not always see what’s inside, so it will be best if you could see the inside of the scrap GF jewelry and if possible ask for the weight of the GF parts separately. Few more examples: Eye glass frames may hold inside a long spring. In most expendable watch bands, only the caps are GF. Clasps must have springs inside.
To summarize, buying scrap GF jewelry can be very lucrative if you know how to price it correctly by yourself. Never trust blindly on the seller description. Whether you process the scrap yourself or sending it out to a refinery, always separate the different types of GF scrap so you could keep track of actual Gold yields average for each type vs. the theoretical numbers. It may take a while to gather this info, but worth it! Your own numbers will never lie to you!