How to save 5-colour project in Illustrator?

neither actually, what are printers doing with jpg files, to start, a reputable printer will not use jg files, they degrade. I have been told, by my design professors always to use uncompressed tiff files, you can make a multi layer file in a tiff. Or just use a 4 channel tiff and a separate file for the spot colours. Then compress it as an 'eps' file from illustrator. An eps is just an overlayered tiff file really.

Either way talk to the printer, request a test print before you do anything, they should be able to rip the files and build you a fairly close digital proof based on your files. The metallics won't print obviously, but make sure that all is clear when you leave the print shop.

Experience tells me that if you are in the wrong here, you will be billed, and very unhappy. But there is no real true way to use spot colours, these can be achieved many ways. But be clear and I would go as far as to supply a working dummy of your project as well. Cover all your bases with anything abnormal from a print shop.

As for what colour is gold, it is actually made from real gold. Well a mix of metals, but all metallic paints are actually metal. You can get samples at the print shop, they always have a swatch book of metallics.

There are a number of different golds in the Pantone library (Window > Swatch Libraries > Colour Books > Pantone Metallic Coated) these are the standards that most printers work to, although there are others – look at a Pantone swatch book to choose the right colour – screen representations of metallic colours are not good. Save the file as a pdf, use the Press Quality default setting in the drop down menu, then open the file in Acrobat and run a preflight on it (Advanced > Preflight > PDF Analysis > Document generates more than four plates) this will tell you how many plates you are using. Check with the printer on the marks he wants (trim crop etc) and the amount of bleed required.