A few more notes on the glass sample book:
You can see that the transparant colour have a differently shaped button than the opaque colours. I have been told that the transparant colours buttons have this shape so that it can be see what the product looks like in both thin and thick shapes. For opaque colours that does not matter so much, so they are a simpler shape.

Unformtunately, the last pages show a decay with a mold. I have seen this in quite a few of the older sample cards. The glass will last for ages, but it is always the paper and the strung that decays first.