This ten book series of various reprints (Gem Series) were published with both green and brown suede covers. Three different gold gilt patterns have been seen on the bottom right of the front cover. Interestingly upon inspection one of the three gold patterns is really the same as another minus a little chunk. The books are 6.5 x 4.5.

If you look closely at the two Paradise Lost books, at first glance the gold gilt patterns on the bottom right might look totally different. But in actuality the green book is just missing a bit of the design on the bottom. Most likely there was a problem in the Altemus printing room and at some point the machine no longer punched out that little bit of missing decoration. I think It is fair to say then that the brown book is older than the green book.

Also shown below is the other format seen in this series. All of the books originally came with labeled boxes.