Yeah, it just needs a brighter spec on the "up" areas. Basically, using the gloss as the spec may work. Looks great so far, just doesn't pop quite enough!
I don't know if it's possible with your engine, but if you can not use a colored spec shader, you may use 2 shader and blend them ... one for the diffuse (and overall big highlights) and one for the colored spec ...
so gave this a shot this weekend, mostly failed. closest I could get was this hard to see it in a still but the sparklies do look colored unless the specular focus is right on them. spec map is monochrome, but it needs to have reflection/environment map to disguise the color spec thats baked into the diffuse.
That's the thing. For example, this dude makes a MOP material in vray http://viscorbel.com/creating-mother-of-pearl-material-with-vray/ But he uses like a mix of 3 materials blended together, which all use anisotropic spec and each has a diferent rotation angle and colored spec, so, its a bit hard to do something like this.
Damn... had high hopes for seeing some cool stuff in this thread. Without colored spec it's going to be pretty hard to re-create the look of the sample. you might be able to get an all white MOP effect with anistropic lighting and a well made aniso-direction map. That seems even more exotic than colored spec though.