All you need is some shimmer spray (I'm using Shimmerz Spritz in Licorice), your lace, and something to catch the extra spray (a cardboard box works great!).
Now, for the fun part. Spray liberally. I mopped up any extra spray with the lace.
And a close-up of the end result. It turned the lace a nice vintage gray color - you can even catch a bit of the shimmer in the photo.
As my 4-year-old would say, easy-peasy. :)
Have a great one!