Item is sold. Closed.
It actually looks more white than silver to me, but since this is my first ever fixed dye and I'm not certain what qualifies as actual white, I'm gonna go ahead and say it's silvery white to be safe.
Here's the ampule itself (enlarged for detail, with itty bitty actual-sized inlay):
And here's what you'd get if you were to dye something with it:
Pretty, no? :3