How does one determine Gold Plate thickness?

[cesariojpn]

So mom is going thru the boxes looking for stuff for a church rummage sale, making a big mess and headache in the process. She called me up to ask about a dish she found. It's a small sake cup looking dish, about 3.25 inches across, about an inch high. Weight on a postal scale is 4 ounces. Has a crane and a turtle with a ship in the middle. There is a Kanji mark and 24KGP on the back.

I have to ask: with such items, what would the gold plate thickness be for such items generally be? I'll try to get some pics later.

[Robarons]

Extremely thin. 24kGP means Gold plate. To put this in comparison here are some definitions:
Gold Filled: 1/20th of the items weight is karat gold, Example a 20 gram 1/20 12k item should have 1 Grams of 12k gold
Rolled Gold Plate: 1/40th of the item weight is karat gold, same idea as above
Heavy Gold Plate (HGE) Gold Plate: This Microns of Gold, meaning its so thin you can scratch, wash off the gold (you cannot do this with Filled or Rolled items)
I would imagine something like a 1/1000 to 1/10,000 ratio if not more for these items

Until recently Goldfilled items were not able to be refined. Places that do accept Goldfilled need like 50 pounds of the stuff with low yields and high fees. And this is high quality stuff, like pocket watch cases and rings from the 1920's. So anything gold plate really has no value scrap wise.

Sounds like a cool antique though. Larger items that are plated in gold are harder to come buy, might have value as that.

[galenrog]

I disagree on value of gold plated items. While the item may have far more value as a collectible, the gold still has value and can be recovered with little trouble by the backyard refiner.

Each item is different, and yes, some items are so thinly plated that I can rub off the plating with my finger. This does not mean that the gold has no value. I have managed to acquire enough gold plated jewelry over the past few months to harvest nearly 30 grams, once the refining was done. I still have more to do.

If you have sufficient gold plated jewelry or other gold plated items, I would be glad to consider a purchase, but I would rather you learn the art yourself. Please visit goldrefiningforum.com and take a look. The learning curve is steep, and there are many safety issues to consider, but it could help you add another feather to your cap where precious metals are concerned. Enjoy.

[tractorman]

This guy has a simple calculator to determine the gold content in plated items:

http://www.goldnscrap.com/index.php?option=com_content&view=article&id=83:estimating-the-value-of-gold-plating&catid=37:scrap-plated-pins&Itemid=37

His focus is on computer pins, but the calculator is perfectly valid if we simply figure the surface area of your dish. Heck, I'll do the math.

The bottom of the dish ... Area = PI x (D/2)^2 = 8.3 sq. in. Multiply that by 2 because there's a top and bottom.

The side of the dish ... The Circumference = PI x D = 10.21 in x 1 in high = 10.21 sq. in. Double it, inside and outside surfaces.

So the total surface area is about 37 sq. in. Using the calculator and 50 microinch plating (very heavily plated) = ~0.5 g of gold ($30.00). 5 microinch plating (very light flash plating) = ~0.05g of gold ($3.00). My guess is you are probably somewhere in between, but that can only be determined after the gold is refined, if you go that route.

[goldsilverpro]

According to this, if it is marked Gold Plate, it must be at least 20 millionths of an inch thick (.000020"). If marked Gold Electroplate, it must be at least 7 millionths thick (.000007"). How closely manufacturers adhere to this is another story.
http://www.google.com/url?sa=t&rct=j&q= ... tQ&cad=rja

Unless you have the expensive equipment necessary to measure the plating thickness, all you can do is make an educated guess based on the information available.

A simple formula for determining value of gold plating, IF you know the thickness:
$ value per square inch = (thickness expressed in inches) X (10.17) X (Gold spot price per troy ounce)

Assuming the gold is 20 millionths thick and the gold spot is $1700,
.000020 X 10.17 X 1700 = $0.346 per square inch of plated area