"Gold is one of the least reactive chemical elements. Gold alone or pure gold does not combine easily with oxygen so it stays shiny, it does not rust nor tarnish, again, that is pure gold."

https://www.onecklace.com/tips/does-real-gold-tarnish/

Gold is often alloyed, since antiquity. Alloy metals may cause tarnish. or result in patina. Electrum is a primary Egyptian example. Egyptians also made red gold by alloying it with copper. JDA.

Thanks, Fred, it's an interesting question and, as with all interesting questions, the answer moves from simple to complicated.

The simple answer is that gold does not tarnish; it doesn't undergo the chemical process that occurs when the surfaces of metals such as silver or copper or alloys like bronze interact with the surrounding air. It can develop a patina, as with your examples I would guess, but that kind of patina doesn't represent a chemical change to the metal itself.

But the answer gets more complicated when we talk about gold that is not 100% pure, as most gold in antiquity was not. The first "gold" coins which seem to have come from Lydia, a kingdom in Western Anatolia in the 8th century BCE, were an alloy of about 50-55% gold with 40-45% silver and a little copper. This appears to have been an artificially controlled alloy rather than a naturally occurring electrum. Probably the main reason for the impurity was to make the gold content less costly, and secondarily to make the coinage less soft and more long lasting.

Still at that point gold doesn't seem to tarnish. How much further on the impurity spectrum do we have to go before tarnishing occurs? I can't find an informed answer to that, but based on my own observation I would say we have to go well below 10 karats to somewhere around 30% gold content.

Let me give a few examples:

1. is a typical Roman gold bracelet, probably 2nd century CE, which is very rare because it is one of the very few examples of Roman gold found near the great port city of Oc Eo which was located on what is now the border between Vietnam and Cambodia. It had been cleaned by a friend before I bought it nearly 30 years ago, and it will never tarnish. It's more than 90% pure.

2. is a gilt image of Avalokiteshvara made in China during the Wei dynasty in the 5th century. The mercury gilding process has left such a pure coating of gold that after all these years there is no tarnishing but there is a patina, and where the gilding has worn away the bronze beneath has tarnished and corroded.

The way I learned it is:

In antique pieces with less than 24K, over a long period of time, some pure gold rises to the surface -creating what appears to be a thin film.

After the raised areas have been handled or polished, the uncleaned, recessed areas appear to be a richer shade of orange. I am not a metallurgist; I do not really understand this process. Is it a chemical change?

Hello will
Long time no see

Hi RM,

It's good to see you here. With respect, I think you may be wrong about the dating of this simple little devotional figure. I've seen several similar dated examples from the Wei dynasties in the fifth and sixth centuries. For instance, one with an inscription on the back that dates it to the year 474 was sold at Christie's in September 2013. The gilding on it has mostly worn away but it's virtually identical to the one that I showed here.

Generally speaking, the later Tang dynasty examples are more elaborate, with flowing robes and mandorlas (the fiery haloes) that are more detailed; they are quite often enthroned, and if standing, frequently have a wider plinth, sometimes in a lotus shape. The movement from simplicity to elaboration is typical, I think, of the wider cultural shifts in those centuries, particularly in the practices of Buddhism.

But having said that, I wouldn't rule out your suggestion entirely. These figures were cast in a variety of different foundries according to the tastes of customers, and in some places older fashions lingered on into later periods.

Cheers,

Will

19th century Japanese ojime. 3/4" or 18mm height. Meiji Era. High carat gold. Notice thin film (tarnish) in the recessed areas. The tarnish on the raised areas has been removed through handling.

http://www.eldreds.com/auctions/gallery.php?keywords=ojime&query=search&searchType=keywords&domain=upcoming

Each time I walk in and out of the store this guard smiles and says "hello." This is why I had the courage to introduce myself, shake hands, and get close to ask for permission to make his portrait. I explained that I collect jewelry and wanted his photo. I am not intending to make fun of him. But I think it is a fun picture.

And thanks for the gold ojime "review", Fred! Those are pretty spectacular and I daresay belong in a museum (someday...).

And now some ancient gold beads:

1. is a group of beads from an early Dvaravati (pronounced Tawarawati) site in Central Thailand. They date from the 4th-6th century. Some are solid gold, others are gold over a resin core. The gold content is high in all of them, from 75% to 90%, and again there is no tarnishing, though there's a very pretty orange patina in places that I ought to look at microscopically and haven't!

2. is a group of beads that seem to date from somewhat earlier (C1-3 perhaps) which were found in Central Thailand also. They seem to be absolutely unique, and I really have no basis to say whether they were made where they were found or somewhere else entirely. For the moment, my best guess is that they might have been made in Central-Northern India and imported, along with carnelian and agate, into Thailand, but that is only a guess. They were found together, but the gold content in the three drum-shaped beads is higher (though still quite low at around 40%) than in the "gold" (25-30%), struts of the nine mainly silver seed-shaped beads. The drum beads show only occasional tarnished patches, while the tarnishing is more generalized on the seed-shaped beads - I clean it off lightly from time to time so that one can see the contrast between the silver and the "gold".

I think in all of this there's an interesting discussion about the social function of gold and the different kinds of value attached to it.

Cheers,

will

"Gender, age, sexuality, race, ability, religion, class, national origin and other intersectional aspects of identity are constructed, negotiated, and performed via sartorial choices. The fashion industry has particularly benefitted from colonialism and imperialism, the labor of immigrants, women, African Americans, Latinx, and appropriation from indigenous peoples and other marginalized groups. This roundtable seeks to shed light on the ways in which we are and are not fully exploring and addressing diversity and inclusion in our field. Our aim is to prompt rich and open dialogue about how our organization can become more diverse and inclusive in practice, membership, scholarship, and conference attendance. We seek nominations of individuals from across all aspects of our discipline: researchers, designers, curators, educators, etc. to discuss ways in which they have incorporated diversity and inclusion into their dress studies practice and to perhaps challenge or provide insight into how all of us can more often do so.
Nominations for the 2019 Scholars’ Roundtable are due by October 15, 2018. More information can be found here or by contacting Dr. Michael Mamp at Michael.Mamp@cmich.edu."

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These were found in a shipwreck in the Phillipine islands. I bought them from Marc Pettibone, who sold in Jatuchak.

is
CUTE

3/4" or 18mm height

tarnish |ˈtärniSH|
verb
lose or cause to lose luster, esp. as a result of exposure to air or moisture: [ no obj. ] : silver tarnishes too easily | [ with obj. ] : lemon juice would tarnish the gilded metal.
• make or become less valuable or respected: [ with obj. ] : his regime had not been tarnished by human rights abuses.
noun
dullness of color; loss of brightness.
• a film or stain formed on an exposed surface of a mineral or metal.
• damage or harm done to something.
DERIVATIVES
tarnishable adjective
ORIGIN late Middle English (as a verb): from French terniss-, lengthened stem of ternir, from terne ‘dark, dull.’

Ancint silk road treasure, i'm buying ancient mixed horads including silver, gold and other metal artifacts, showing you Gold bead, probably gold button or earring and gold bar, not cleaned, looks to be leeched, and corroded, if buried thousands of years open/loose inside oxided grave, corrosion or gold discoloring does occur and sometimes in damaged artifacts.