I can confirm that Larry's (Headphile) replacement cable for the 590 is silver. He has a new silver/copper replacement cable called the Black Max but it is not available for certain headphone replacement cables like the HD 590.
So silver is your only choice for that one. I have a 2 meter HD 590 Headphile cable that I use with my computer setup. It's a very nice sounding cable. It tames the low end of the HD 590 to some extent and gives it a smooth sounding midrange. The highs of the 590 are not the best but they don't sound too bad with Larry's cable. I've also ordered an Equinox HD 590 cable to compare them soundwise, but it won't arrive for 5 months.
Certainly from the standpoint of ergonomics, Larry's cables have no competition. His cables are light, very flexible, and have a nice cloth feel with little or no microphonics, unlike techflex cables which can be wiry, spindly, relatively heavy and inflexible (the Equinox is also highly microphonic I have read). Depending on what you need, Larry's cable may very well be the best option out there.
I'd also like to mention that his cables are as well built as any I have ever seen and built better than some I have seen that cost significantly more. And Larry has exceptional customer service. He allowed me to switch my first E-mu cable for a smaller size, and was very helpful in general with lightning fast turnaround.
I have Headphile cables for my HD 25, HD 212, E-MU 404 and HD 590. My HD 212 is the first one with a silver Headphile cable to replace the terrible 10 foot stock wire. The HD 212 is my favorite outdoor portable phone, and Larry's cable makes it dramatically better, improving the sound in every imaginable way (from taming the overexagerrated bass, to smoothing the midrange and easing the extension of the highs).
The improvement is especially dramatic because the stock cable is so bad to begin with. When I plug the stock cable in I immediately notice how harsh, strained and tired the stock cable sounds. Larry's cable is smooth and effortless in comparison and it makes the HD 212 sound better in every way, with more detail and a nice overall musical sound.