Looks like Wilton Pearlized Gold sugar to me;
I'd randomly paint gum glue on the ombre fondant and gently apply the sugar. Probably other ways, too.
I think it might be "edible gelatin glitter". There are a couple of tutorials available if you search for that. HOWEVER, we tried the "edible" gelatin sequins at work one day, and while they might technically be "edible", they are really NOT for eating… fyi.
I agree with maybenot, looks like pearlized sugar crystals randomly sprinkled on the cake. The lighting on the picture is not very good so it is difficult to see the exact color or the sugar. Piping gel brushed on the cake would adhere the sugar too. I used the crystals on a St. Patty's day cake last year, I got them here;
to replicate that the first thing i'd test/try is dessicated coconut -- fancy word for coconut in a food processor or spice grinder aka coffee grinder/mill -- just see how that goes -- how close i could get to that texture and then color it and apply -- but then airbrush it after application so i don't nick the airbrushing on the cake while applying it --
or maybe take the gold sugar and grind that up -- because it's not an even size like sugar is -- it's a varied texture that doesn't seem faceted like sugar is faceted --
it's a beautiful design