Wow, that is an excellent material, it would be quite the fluke to find the same one.
I would suggest creating it "on the fly" in bright orange satin and making a diamond shape stencil to paint on the pattern. It might take some time but the effect would be awesome.
I also think it would be easiest to make the fabric. I'd probably make it out of a cotten blend so it'd be a lot easier to sew. Simplicity has a clown patter, while it's not a perfect match to the Pierrot picture you linked. You could probably use a jacket or robe pattern to go over your diamond fabric.
I did find some free patterns for the hat and collar. Free Directions to Sew Clown Collar and Cuffs to Sew An Easy Clown Halloween Costume
If you can find a black/white diamond fabric in cotton or a cotton blend (or linen) then you could get orang dye and make it black/orange. The black would just look a little richer - but the white would go orange! (dying fabric is pretty easy in the washer, just make sure to get enough bottles to make it BRIGHT and run the washer through a cycle or two to remove the dye)