Playing around with some spot colors, I've found that named colors which contain a number in the name don't display properly, but only in Preview.app on MacOSX.

i.e.

@prince-color Pantone123 {
	  alternate-color: rgb(234,171,0);
}

.bla{
	color:prince-color(Pantone123);
}

displays in a shade of blue on Preview.app, but displays as the appropriate yellow on Acrobat.

An otherwise identical color named "PantoneOneTwoThree" displays appropriately.

Strangely, but this might help debugging; these colors-with-numbers-in-the-name seem to always display in shades of blue, but I can't yet fit together any connection between the numbers contained in the names and shorthand hex codes or anything else...

In any case, this wouldn't be bothersome if Pantone colors weren't generally indexed with a number, meaning "Pantone123" or "P123" would be common names for a spot color.

Of course, this may be a bug in Preview.app, but spot-color PDF's generated with other engines display fine…

This wouldn't be the first bug in Preview that's bitten us, but we would still like to avoid triggering it if possible.

Would you be able to email me a PDF with named colors that does work? Perhaps the names containing numbers need to be encoded or escaped in a particular way to work with MacOS X Preview.

For the record, this issue appears to have been resolved by rebooting the machine, but we have changed the way Prince generates spot colors to be more consistent with InDesign, just to be sure.