http://www.straightdope.com/mailbag/mwhtgold.html
I was just wondering- if 24 Karat gold is 99.99 % gold, what is the other 0.01 % of?
(edited to make the post a clickable link)
(this post has been edited by Arnold Winkelried)
I would guess it’s impurities from the refining process?
Another site I found, “What you should know about Karat Gold” says that twenty-four karat gold is 100% gold.
In all modesty, here’s a mailbag article I wrote that relates to this: http://www.straightdope.com/mailbag/mwhtgold.html
Jill, your nicely done article was essentially correct.
If I were to pick some nits, they would be:
Actually, class rings have always been 10k gold, whether white or yellow. I buy hundreds of them over the counter every year, and that’s just what they are. By law, they are marked as such. The only exception being that, these days, class rings are also offered to students made out of non-gold metal, which I jokingly refer to as kryptonite rings. Essentially in the US nothing is made out of 12k gold.
10k gold jewelry has become very available in this country in the last 5 years or so as it can be manufactured and sold more cheaply that 14k. If this is “promotional” jewlery, then so be it. Whether it is brittle depends on what it is alloyed with, and what kind of jewelry is being made. A 10k class ring is harder and more durable than one made of 18k gold.
Assuming the gold to be alloyed with nothing but copper, yes, yes a 10k gold ring is more brittle than an 18k one. But it is harder and shows wear less. I don’t think brittle enters into the jewelry aspect of the equation.
This has me wondering what the remaining .56% is in my Ivory soap.
Cecil has already answered this question. Actually, there’s two different versions of this column in the archives. They both have the same info and are answers to the same question. I’m not sure why there are two, but at a guess, one is the original column and the other is a rewrite for the book.
http://www.straightdope.com/classics/a930820.html
http://www.straightdope.com/classics/a4_157.html
Not universally. MIT “brass rats” have always been available in a range of alloys and gold-substitutes. The class of 2000 version is available in 10K, 14K, 18K, 21K, Polara, and Siladium (I have no idea what those last two are).
dtilque thanks for the Ivory info. I should have looked it up myself, but plead not enuf sleep.
JohnF You are certainly right. What I should have said is that 95+ % of all the class rings that I have purchased over the counter since 1971 have been 10k gold.
In the old days, prior to 1980 or so, when gold skyrocketed, 99% of all rings bought were probably 10k. Now we see 80% 10k gold and 20% Polara/Siladium/Kryptonite. The in-between gold ones you hardly ever see. I can only assume most people bought the cheapest gold one they can afford, or the non-gold ones.
Thanks for the help.
IIRC the Polara/Siladium/Kryptonite rings are the ultra-cheap class rings for those who can’t afford gold, but still want a class ring. Instead of $400, they are $100 (estimates). They have a silvery color.
Around these parts, they call that stuff ‘Lustrium’. In high school, we joked that it was an alloy of silver and aluminum. There was another metal named something like ‘Aurora’ which (judging from the price) was probably brass.
What is “green gold” -does it contain real Au, or is it an alloy of base metals?
It’s gold. If you add a greater proportion of silver to the gold alloy you get green gold (sometimes cadmium and zinc added, too); if you add more copper you get rose gold; more nickel and/or palladium and you get white gold (which is still faintly yellow, but generally plated with rhodium, as the mailbag article notes). I generally see rose and green gold in 14k, but there’s no real reason why they couldn’t be a lower or higher karatage, although the more pure gold you have in the alloy the yellower the color.
I always thought the “lustrium” stuff was stainless steel; silver would tarnish and aluminum would feel light and cheap.
I don’t know what the particular alloy was, but at my high school, the glass gem in the fake silver setting was $190. No, thank you; it’d be cheaper to just buy the silver (or pewter) myself and make the stupid thing.
24 karat gold is hypothetically 100% pure gold. There are technical difficulties that prevent such high purity from being attained. Grades such as .995, .999, .9995, .9999, and .99999 fine gold are all availible on the market.
http://searchpdf.adobe.com/proxies/2/17/69/50.html has a link to an article in pdf format from Gold Bulletin 1998, 31(2) that describes a study of impurities found in high-purity gold. For example, .9999 fine gold was found to contain the following impurities (in parts per million):
Silver 90
Copper 50
Palladium 50
Silicon 50
Magnesium 30
Arsenic 30
Lead 20
Iron 20
Bismuth 20
Tin 10
Chromium 3
Nickel 3
Manganese 3