I've seen this fabulous rainbow spectrum stamp from Germany on a few German Postcrossing postcards now. I love it! The colors just jump out when I pull the postcards from my mailbox.
This stamp honors German optician Josef von Fraunhofer. Honestly, I'm most excited about the fine rainbow spectrum. My love of rainbows is childish, primal, and somewhat inexplicable.
Along with the fine postcard surprises one gets from Postcrossing, I am often just delighted with the postage stamps, too.