Mitsui made Gold DVDRs for a while... but they couldn't make them work very well, so they pulled the whole line. I've heard reports they are still trying to pull it off though, and may re-release the product line later.
The 'Mitsui Gold Ultra 24x' was an excellent piece of media and damn expensive, too (around 1,40€ apiece) ... it featured a true 24 karats gold reflector and phtalocyanine dye. Personally, I did never encounter media with lower BLER (even TY was ... erm ... 'worse').
Problem is that Mitsui had a cheaper media type simply called 'Mitsui Gold' which was a PITA (Pain In The Ass, that is) ... low compatibility, paired with high error rates and low life expectation made Mitsui's reputation go down the drain.
Unfortunately, they did not produce any more Gold Ultra because nobody bought them ... additionally, after converting Mitsui to MAM-E, everything got worse so MAM-E cannot be considered a quality manufacturer any more these days (take a look at their DVD media - it's pure crap on any burner).