[eric nixon]

I'm sorry Hatts it is a valid material request, and it is a bit tricky to get the right look, saying 15 mins was a bit cheeky, but also factual.

The tricky bit is getting the centre smooth while the edges are a bit rougher, you need two additive layers with different roughness, so one layer is bright pink R0, black R90, other layer with red R90 black R0.

[bograt]

there is a degrading tendency when you approach something with too much thought.

I totally agree, but what are you referring to?

Eric, from the reference I think your falloff is wrong.
The reference image he posted looks like it has a slightly glassy falloff rather than purely metallic.



Here are 4 approaches for comparison.
In the front: aluminium ball within a transmissive ball
On the left: aluminium ball and an exact duplicate with transmissive material with 0.05cm displacement (white map/8xsub/on the fly)
On the top: the original material I posted
On the right: the original material with an additive Black/90 Black/0, 1.35Nd force fresnel layer
No noticeable increase in render time with displacement applied.

I think you can achieve the the hue shift accurately without trickery, you get a similar effect with the wizard copper

[hatts]

there is a degrading tendency when you approach something with too much thought.

Ok, shall I fire up Rhino and use the stock renderer then? Maybe for material I'll pick "Shiny"

@eric: I like where you're going with the second layer of differing roughness, I will explore that

Eric, from the reference I think your falloff is wrong.

Would agree here, reflections discolor as they bounce

@bograt: I'm drawn to the rightmost solution in your four spheres, it's simple but seems to get the falloff right.

I just grabbed a material swatch:

[bograt]

I agree, the example on the right is the one I would choose.
Here is the material with subtle 0/90 degree hue shift:

Note the hue shift in the repeated reflections
Its a very simple material really, 1bdsf, no force fresnel, 1 additive 1.35Nd force fresnel layer to serve as the top layer.
The roughness is 0 but increasing to 1.5 can improve the look. (Edit: in fact looking at your swatch it could maybe go even further, or 2 bdsfs - one double the roughness of the other)
By the way, I only roughly matched the colour. it would be easy to get it spot on.

[eric nixon]

Update with boosted laquer and darkened fall-off from feedback and new reference images, dropped the pink coating, that wasnt working as expected.



And some versions with shifted hues. Its a cute material, harder than it looks... and quite smoothy < sorry for the technical terminology.

[eric nixon]

OMG, having saved all those, I just remembered theres a PROPER way to do this which requires no eyeballing

Hatts you could find out which metal they use to coat the steel and the coatings thickness, for example here is a coating of cobalt silicide @ 285nm;



Just add a coating and spec a custom ior, the bsdf underneath becomes very muted with colourful coatings unless its transparent. You can set the bsdf colours to black to maximise the coatings saturation... so hardly any tweaking.
Also there is a quick way to see what kind of rainbow effect each type of ior-coating provides, just load a gradient into the coatings thickness slot, and spec a sensible range - say 20 to 800.

[bograt]

OMG, having saved all those, I just remembered theres a PROPER way to do this which requires no eyeballing

Bravo!
Sort of goes against his request to avoid force fresnel but a very good solution either way.

[eric nixon]

You can adjust the colour by changing the coating thickness, the only colour thats seems rare is pure red, I only found one ior which gave a decent red so far. Some iors give an R2 hue-shift effect (like this one) some dont.

[hatts]

Thank you to eric and bograt, this was all very helpful.