I'd say paint the mask black, then find a pair of sunglasses with gold shades, then pop out the lenses for it : o
You can either try and cut them to fit to the eye holes if you have the resources to do so, or you can tape them together, and then tape or glue them to the inside of your mask. I'd try and fit them to the eye holes, but not everyone has the patience, or is able to do that. Or time.
When I cosplayed Zacharie from Off, I made the mask and used some black fabric, but stretched it out so i could still see around, but others couldn't see my eyes. No matter how stretched out I got the fabric however, it was still very hard to see, and I had to have my friend help me. Case in point, fabric looks great, but doesn't alwawys work : o . Just something to keep in mind whenever you make another mask where the eyes are covered. Not to say it doesn't work, but just saying it's not always the best option!
I hope this helps you. Have fun making the rest of your cosplay, and remember to post a picture when you're done! I'd love to see it : 3c