Why is gold yellow?

It absorbs most colors of light and reflects "yellow" ? Randy

Well hell why is silver, silver or copper, copper colored?

------- I forgot more about ponds and koi than I'll ever know!

I'm more of a fan of white gold

The simple explanation is that the reflection spectrum of gold appears to be something like yellow to the human eye because little blue light is reflected by a metallic gold surface. The complicated explanation has to do with Fermi levels and excited electrons. Gold and copper are yellowish/reddish for similar reasons at that level of analysis. They do not re-emit light at various parts of the blue end of the spectrum for reasons best explained in terms of subatomic physics.

The first sentence above is good enough for me.

-- Ed Huntress

Randy is right, we see the wavelength reflected from the surface, the others are absorbed. Silver is interesting then because what wavelength is reflected? In Silver, you see a reflected image. So does it absorb all, or reflect all?

Big Al PE Chem. Engineer and Chemist Birmingham, AL, USA

"Lustre" is a quality of all metals that is separate - probably independent of - color. You see a reflected image in all polished metal.

What I've read makes it more the domain of an electron spin-resonance physicist's than of a metallurgist's to explain the color any substance absorbs or reflects.

Some substances not only reflect only a small range of colors, but also can convert other absorbed frequencies into their preferrentially reflected color, so that the amount of energy "reflected" is more than that band's content in the original light source.

LLoyd

How about: Because it is NOT any other color. Being NOT any other color only leaves Yellow. This explanation is necessary and sufficient unless you desire to change it's color. Then you are in for a ride on the subatomic physics train. The train ride is like going to a fire hydrant to get a drink of water. More on you than in you.

Hooookay. For a moment I thought we'd escaped complication on this one, but my instincts tell me that you've just thrown a switch and there's a train coming back at us, that somebody is going to point out that it's not really "yellow" but rather *all* colors except for a few near the blue end of the spectrum...but maybe whoever is inclined to say something like that didn't notice, or has to go somewhere now and will forget when he gets back...d8-)

-- Ed Huntress

You see evidence of that when viewing a collection of pure gold shot. The color is almost breathtaking, yet not nearly as pretty when you view individual pieces. The color, when reflected from piece to piece, is much darker----and prettier.

Harold

First: "Yellow" is a human, english, perceptual term that is based on common responses to certain visual inputs (wavelength, intensity, duration, wavelength mixture, etc.,) Other species don't see colors, they respond to wavelengths. Other cultures may not see 'yellow' as we do. Classification of color is dependent to a certain extent on culture and the language it is being referenced in.

Second: The appearance of yellow varies greatly between individuals and even between eyes of a given individual.

I remember a very interesting demonstration by one of the greats of the visual perception field where trained subjects were asked to match 'colors' of light presented to one eye with the other eye. The yellow matches went from what I call 'red' to nearly 'green'.

Beauty is truly in the eye of the beholder.

All the nuances of of appearance that occur in real life objects have filled books, lectures and courses for hundreds of years.

Karl Pearson

Gold or any other metal and also other substances have a specific atomic srtucture. Arrangement of the electrons in the last orbit and their unique energy level determine the frequencies that are absorbed or reflected. Is all a Quantum Physics description of the light absorbtion/reflection. I am no expert but the physicists have this subject well understood to the point that have programs that can determine the color and brighteness given the substance, the light source and angles. MG

reminds me of a "how it is made" tv show where they had gold coins minted in canada with diffraction gratings stamped into them on the verso, produced rainbow colors, speaking of nano-whatevers...

b.w.

And gold-leaf, when applied to awindow - - you look at stuff through it and all is a beautiful greenish-blue.

I wonder what color appears through thin coatings, like astronauts' visors?

Flash

And gold-leaf, when applied to awindow - - you look at stuff through it and all is a beautiful greenish-blue.

I wonder what color appears through thin coatings, like astronauts' visors?

Flash

that's actually a dichroic coating. it has a different reflective and refractive color, so the color you see looking at the glass isn't the color that soemone looking through the glass would see.

i use it in glass work frequently.

regards, charlie

i think the question should be, "what colour is pure, 24k gold? as gold comes in different alloys and has different colours.

In my experience, "pure 24K" is almost impossible to obtain by ordinary refining methods! Gold from different places, almost always has a slight colour difference.

Steve R.

24K is a techncal designation, 24 parts out of 24 being gold. Most reputable refiners are more than happy to specify how close they are, typically you'll see .999 or .9995 fine as the spec that they meet. Unless you're going to tell me that they're lying, that's close enough to 24K for me. And, every 24K bullion coin I have, .999 or .9995, are all the same color - I guess I'd describe it as "gold" colored.