Often made of reddish wax, I bear a family's crest. Found upon olden letters of import, fraud prevention is what I do best.

Small and round, yet worth I hold, passed through hands more times than told.

When you look into a mirror, what do you see in it's reflection?

A time when I'm green, A time when I'm brown. But both of these times, Cause you to frown. But just in between, For a very short while. I'm perfect and yellow, And cause you to smile. What am I?

I am the invisible paint on the canvas of silence. I can travel through walls without a door and touch your heart without a hand. I am made of math, but I feel like magic. What am I?