To swatch or not to swatch?

I have, for some time now, thought a swatch card a very useful little device; tiny pieces of fabric all lined up in a row for your viewing and choosing pleasure.

So, when I set out to create swatch cards for MAKE.GOOD studio I asked myself the following questions:
1. What is the convention for organizing fabric swatches?
2. How would I organize fabric swatches?
3. How might this card be useful to a client?
A quick study of the above questions provides a bit of insight into my way of thinking about any design problem. I think about what has been done before, my own, unbiased thoughts about how things are done, and then how the user may want to see things done.
At the end of the day, after much consideration, the answer was right in front of me on the shelves of my studio. You see, I organize my fabric by type first and second by how major a player it is in the collection. The result is four categories, wool, linen, cotton, specialty. The result, it turns out, is intuitive...to me and hopefully to everyone.
Regardless, it is so satisfying to see all the pretty colors gathered together, organized and ready to be picked.
Ok, so it was also a ton of fun naming the colors. Petra is my favorite. Can you find it, and do you know why it's called Petra? (and don't cheat and use the internet to find the answer)